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Soft-collinear effects in prompt photon production | We extend next-to-leading logarithmic threshold and joint resummation for
prompt photon production to include leading collinear effects. The impact of
these effects is assessed for both fixed-target and collider kinematics. We
find them in general to be small, but noticeable.
|
Python for Education: Computational Methods for Nonlinear Systems | We describe a novel, interdisciplinary, computational methods course that
uses Python and associated numerical and visualization libraries to enable
students to implement simulations for a number of different course modules.
Problems in complex networks, biomechanics, pattern formation, and gene
regulation are highlighted to illustrate the breadth and flexibility of
Python-powered computational environments.
|
On the dynamical mass generation in confining Yang-Mills theories | The dynamical mass generation for gluons is discussed in Euclidean Yang-Mills
theories supplemented with a renormalizable mass term. The mass parameter is
not free, being determined in a self-consistent way through a gap equation
which obeys the renormalization group. The example of the Landau gauge is
worked out explicitly at one loop order. A few remarks on the issue of the
unitarity are provided.
|
L^2 harmonics forms on non compact manifolds | The source of these notes is a series of lectures given at the CIMPA's summer
school "Recent Topics in Geometric Analysis".
|
Restrictions on sterile neutrino parameters from astrophysical
observations | Adding 3 right-handed (sterile) neutrino to the Standard Model (SM) can solve
several "beyond the Standard Model" problems within one consistent framework:
explain neutrino oscillations and baryon asymmetry of the Universe and provide
a dark matter (DM) candidate. In this talk I will present current status of
astrophysical searches for the DM sterile neutrino.
|
On limit cycles appearing by polynomial perturbation of Darbouxian
integrable systems | We prove an existential finiteness Varchenko-Khovanskii type result for
integrals of rational 1-forms over the level curves of Darbouxian integrals.
|
Lectures on (abelian) Chern-Simons vortices | Various aspects including the construction and the symmetries of Abelian
Chern-Simons vortices are reviewed. Extended version of the Lectures delivered
at NIKHEF (Amsterdam), July 2006. Typos corrected, some refernces added.
|
Characterization of polynomials | In 1954 it was proved if f is infinitely differentiable in the interval I and
some derivative (of order depending on x) vanishes at each x, then f is a
polynomial. Later it was generalized for multi-variable case. In this paper we
give an extension for distributions.
|
Slowly rotating pulsars | In the present work we investigate one possible variation on the usual static
pulsars: the inclusion of rotation. We use a formalism proposed by Hartle and
Thorne to calculate the properties of rotating pulsars with all possible
compositions. All calculations were performed for zero temperature and also for
fixed entropy equations of state.
|
On the Smooth Feshbach-Schur Map | A new variant of the Feshbach map, called smooth Feshbach map, has been
introduced recently by Bach et al., in connection with the renormalization
analysis of non-relativistic quantum electrodynamics. We analyze and clarify
its algebraic and analytic properties, and we generalize it to non-selfadjoint
partition operators $\chi$ and $\chib$.
|
Electrically charged pulsars | n the present work we investigate one possible variation on the usual
electrically neutral pulsars: the inclusion of electric charge. We study the
effect of electric charge in pulsars assuming that the charge distribution is
proportional to the energy density. All calculations were performed for zero
temperature and fixed entropy equations of state.
|
The moduli space of cubic fourfolds | We describe the GIT compactification of the moduli space of cubic fourfolds,
with a special emphasis on the role played by singularities. Our main result is
that a cubic fourfold with only isolated simple (A-D-E) singularities is GIT
stable. Conversely, with some minor exceptions, the stability for cubic
fourfolds is characterized by this condition.
|
Python Unleashed on Systems Biology | We have built an open-source software system for the modeling of biomolecular
reaction networks, SloppyCell, which is written in Python and makes substantial
use of third-party libraries for numerics, visualization, and parallel
programming. We highlight here some of the powerful features that Python
provides that enable SloppyCell to do dynamic code synthesis, symbolic
manipulation, and parallel exploration of complex parameter spaces.
|
Spectrum of Yang-Mills Theory in D=3+1 | We give a comparison of the spectrum of Yang-Mills theory in $D=3+1$,
recently derived with a strong coupling expansion, with lattice data. We verify
excellent agreement also for 2$^{++}$ glueball. A deep analogy with the $D=2+1$
case is obtained and a full quantum theory of this approach is also given.
|
Local structure of the moduli space of K3 surfaces over finite
characteristic | Let k be a perfect field of characteristic p > 2. In this note, we show that
the local moduli space of a non-supersingular K3 surface over k with trivial
deformation of the associated enlarged formal Brauer group admits a natural
p-divisible formal group structure.
|
Cargese lectures on string theory with eight supercharges | These lectures give an introduction to the interrelated topics of Calabi-Yau
compactification of the type II string, black hole attractors, the all-orders
entropy formula, the dual (0,4) CFT, topological strings and the OSV
conjecture. Based on notes by MG of lectures by AS at the 2006 Cargese summer
school.
|
A Perverse Sheaf Approach Toward a Cohomology Theory for String Theory | We present the construction and properties of a self-dual perverse sheaf S_0
whose cohomology fulfills some of the requirements of String theory as outlined
by T. Hubsch in hep-th/9612075. The construction of this S_0 utilizes
techniques that follow from MacPherson-Vilonen (Inv. Math. vol. 84, pp.
403-435, 1986). Finally, we will discuss its properties as they relate to
String theory.
|
The effect of dissipation on quantum transmission resonance | Quantum transmissions of a free particle passing through a rectangular
potential barrier with dissipation are studied using a path decomposition
technique. Dissipative processes strongly suppress the transmission probability
at resonance just above the barrier resulting in an unexpected reduction of the
mean traversal time through the potential barrier.
|
On the Marginal Distributions of Stationary AR(1) Sequences | In this note we correct an omission in our paper (Satheesh and Sandhya, 2005)
in defining semi-selfdecomposable laws and also show with examples that the
marginal distributions of a stationary AR(1) process need not even be
infinitely divisible.
|
PVLAS experiment, star cooling and BBN constraints: Possible
interpretation with temperature dependent gauge symmetry breaking | It is known that the kinetic mixing of photon and another U(1)_ex gauge boson
can introduce millicharged particles. Millicharged particles $f$ of mass 0.1 eV
can explain the PVLAS experiment. We suggest a temperature dependent gauge
symmetry breaking of U(1)_ex for this idea to be consistent with astrophysical
and cosmological constraints.
|
Geometric structure of sumsets | Given a finite set of lattice points, we compare its sumsets and lattice
points in its dilated convex hulls. Both of these are known to grow as
polynomials. Generally, the former are subsets of the latter. In this paper, we
will see that sumsets occupy all the central lattice points in convex hulls,
giving us a kind of approximation to lattice points in polytopes.
|
Towards Antihydrogen Confinement with the ALPHA Antihydrogen Trap | ALPHA is an international project that has recently begun experimentation at
CERN's Antiproton Decelerator (AD) facility. The primary goal of ALPHA is
stable trapping of cold antihydrogen atoms with the ultimate goal of precise
spectroscopic comparisons with hydrogen. We discuss the status of the ALPHA
project and the prospects for antihydrogen trapping.
|
A Geometrical Approach towards Entanglement | We have studied the concurrence of two-site entanglement and have shown that
it is related to the geometric phase accumulated due to a complete rotation of
the entangled state. The geometric phase and hence the concurrence is evaluated
for transverse Ising model and antiferromagnetic chain which is found to be in
good agreement with that obtained by other methods.
|
Irreducible three-loop contributions to the pressure in Yang-Mills
thermodynamics | In the effective theory for the deconfining phase of SU(2) Yang-Mills
thermodynamics we compute estimates for the moduli of the irreducible
three-loop diagrams contributing to the pressure. Our numerical results are in
agreement with general expectations.
|
Jet schemes, arc spaces and the Nash problem | This paper is an introduction to the jet schemes and the arc space of an
algebraic variety. We also introduce the Nash problem on arc families.
|
Gravitomagnetism, Frame-Dragging and Lunar Laser Ranging | We discuss here the measurement of gravitomagnetism and frame dragging with
Lunar Laser Ranging, LAGEOS and LARES Satellites, and Gravity Probe B.
|
Generators of Jacobians of Hyperelliptic Curves | This paper provides a probabilistic algorithm to determine generators of the
m-torsion subgroup of the Jacobian of a hyperelliptic curve of genus two.
|
(Erratum) An f(R) gravitation for galactic environments | Without abstract.
|
Higher-dimensional Temperley-Lieb algebras | A category which generalises to higher dimensions many of the features of the
Temperley-Lieb category is introduced.
|
Extreme points of the set of density matrices with positive partial
transpose | We present a necessary and sufficient condition for a finite dimensional
density matrix to be an extreme point of the convex set of density matrices
with positive partial transpose with respect to a subsystem. We also give an
algorithm for finding such extreme points and illustrate this by some examples.
|
J-class weighted shifts on the space of bounded sequences of complex
numbers | We provide a characterization of $J$-class and $J^{mix}$-class unilateral
weighted shifts on $l^{\infty}(\mathbb{N})$ in terms of their weight sequences.
In contrast to the previously mentioned result we show that a bilateral
weighted shift on $l^{\infty}(\mathbb{Z})$ cannot be a $J$-class operator.
|
Statistical-mechanical description of quantum entanglement | We present a description of finite dimensional quantum entanglement, based on
a study of the space of all convex decompositions of a given density matrix. On
this space we construct a system of real polynomial equations describing
separable states. We further study this system using statistical mechanical
methods. Finally, we apply our techniques to Werner states of two qubits and
obtain a sufficient criterion for separability.
|
Eigenfunctions of the two-dimensional Moshinsky-Szczepaniak Oscillator | While the usual harmonic oscillator potential gives discrete energies in the
non-relativistic case, it does not however give genuine bound states in the
relativistic case if the potential is treated in the usual way. In the present
article, we have obtained the eigenfunctions of the Dirac oscillator in two
spatial dimensions, adapting the prescription of Moshinsky.
|
Natural boundary of Dirichlet series | We prove some conditions on the existence of natural boundaries of Dirichlet
series. We show that generically the presumed boundary is the natural one. We
also give an application of natural boundaries in determining asymptotic
results.
|
Some remarks on generalized roundness | By using the links between generalized roundness, negative type inequalities
and equivariant Hilbert space compressions, we obtain that the generalized
roundness of the usual Cayley graph of finitely generated free groups and free
abelian groups of rank $\geq 2$ equals 1. This answers a question of J-F.
Lafont and S. Prassidis.
|
Shearfree perfect fluids with solenoidal magnetic curvature and a
gamma-law equation of state | We show that shearfree perfect fluids obeying an equation of state p=(gamma
-1) mu are non-rotating or non-expanding under the assumption that the spatial
divergence of the magnetic part of the Weyl tensor is zero.
|
$A^\nabla$-tensors on lightlike hypersurfaces | This paper introduces $\anabla$-tensors on lightlike hypersurfaces $M^{n+1}$
of signature $(0,n)$, $(n\geq 1)$ and investigates on their properties in
connection with the null geometry of $M$. In particular, we show that there is
an interplay between existence of $\anabla$-tensors of certain type and
lightlike warped product structures.
|
A note on conformal connections on lightlike hypersurfaces | Degenerate submanifolds of pseudo-Riemannian manifolds are quite difficult to
study because there is no prefered connection when the submanifold is not
totally geodesic. For the particular case of degenerate totally umbilical
hypersurfaces, we show that there are "Weyl" connections adapted to the induced
structure on the hypersurface. We begin the study of these with their holonomy.
|
Decay channels and charmonium mass-shifts | The discovery in the last few years of the $X, Y$ and $Z$ states of the
extended charmonium family has highlighted the importance of the closeness of
decay channels to an understanding of these mesons. We aid this debate by
illustrating a simple calculational procedure for including the effect of open
and nearby closed channels.
|
Four-dimensional Painlev\'e systems of types $D_5^{(1)}$ and $B_4^{(1)}$ | We find and study a five-parameter family of four-dimensional coupled
Painlev\'e V systems with affine Weyl group symmetry of type $D_5^{(1)}$. We
then give an explicit description of a confluence from those systems to a
four-parameter family of four-dimensional coupled Painlev\'e III systems with
affine Weyl group symmetry of type $B_4^{(1)}$.
|
L^2-Betti numbers of plane algebraic curves | In [DJL07] it was shown that if A is an affine hyperplane arrangement in C^n,
then at most one of the L^2-Betti numbers of its complement is non--zero. We
will prove an analogous statement for complements of any algebraic curve in
C^2. Furthermore we also recast and extend results of [LM06] in terms of
L^2-Betti numbers.
|
Realizations of Seifert matrices by hyperbolic knots | Recently Kearton showed that any Seifert matrix of a knot is S--equivalent to
the Seifert matrix of a prime knot. We show in this note that such a matrix is
in fact S--equivalent to the Seifert matrix of a hyperbolic knot. This result
follows from reinterpreting this problem in terms of Blanchfield pairings and
by applying results of Kawauchi.
|
World Graph Formalism for Feynman Amplitudes | A unified treatment of Schwinger parametrised Feynman amplitudes is suggested
which addresses vertices of arbitrary order on the same footing as propagators.
Contributions from distinct diagrams are organised collectively. The scheme is
based on the continuous graph Laplacian. The analogy to a classical statistical
diffusion system of vector charges on the graph is explored.
|
Twisted conjugacy classes in R. Thompson's group F | In this short article, we prove that any automorphism of the R. Thompson's
group $F$ has infinitely many twisted conjugacy classes. The result follows
from the work of Matthew Brin, together with a standard facts on R. Thompson's
group $F$, and elementary properties of the Reidemeister numbers.
|
Quantum decoherence in the theory of open systems | In the framework of the Lindblad theory for open quantum systems, we
determine the degree of quantum decoherence of a harmonic oscillator
interacting with a thermal bath. It is found that the system manifests a
quantum decoherence which is more and more significant in time. We calculate
also the decoherence time scale and analyze the transition from quantum to
classical behaviour of the considered system.
|
Five-parameter family of partial differential systems in two variables | We find a five-parameter family of partial differential systems in two
variables with two polynomial Hamiltonians. We give its symmetry and holomorphy
conditions. These symmetries, holomorphy conditions and invariant divisors are
new.
|
Generation of strongly chaotic beats | The letter proposes a procedure for generation of strongly chaotic beats that
have been hardly obtainable hitherto. The beats are generated in a nonlinear
optical system governing second-harmonic generation of light. The proposition
is based on the concept of an optical coupler but can be easily adopted to
other nonlinear systems and Chua's circuits.
|
The center of the generic algebra of degree p | Let $F$ be an algebraically closed field of characteristic zero, and let $p$
be an odd prime. We show that the center of the generic division algebra of
degree $p$ is stably rational over $F$. Equivalently, if we let $V=M_p(F)
\oplus M_p(F)$ and $PGL_p$ act on $V$ by simultaneous conjugation, then we show
that the function field of the quotient variety $V/PGL_p$ is stably rational
over $F$.
|
Uniqueness of solutions of Ricci flow on complete noncompact manifolds | We prove the uniqueness of solutions of the Ricci flow on complete noncompact
manifolds with bounded curvatures using the De Turck approach. As a consequence
we obtain a correct proof of the existence of solution of the Ricci harmonic
flow on complete noncompact manifolds with bounded curvatures.
|
Elimination Theory for Tropical Varieties | Tropical algebraic geometry offers new tools for elimination theory and
implicitization. We determine the tropicalization of the image of a subvariety
of an algebraic torus under any homomorphism from that torus to another torus.
|
Z Boson Propagator Correction in Technicolor Theories with ETC Effects
Included | We calculate the Z boson propagator correction, as described by the S
parameter, in technicolor theories with extended technicolor interactions
included. Our method is to solve the Bethe-Salpeter equation for the requisite
current-current correlation functions. Our results suggest that the inclusion
of extended technicolor interactions has a relatively small effect on S.
|
Cascading Quivers from Decaying D-branes | We use an argument analogous to that of Kachru, Pearson and Verlinde to argue
that cascades in L^{a,b,c} quiver gauge theories always preserve the form of
the quiver, and that all gauge groups drop at each step by the number M of
fractional branes. In particular, we demonstrate that an NS5-brane that sweeps
out the S^3 of the base of L^{a,b,c} destroys M D3-branes.
|
A consistent formalism for the Thomas-Ehrman Level Displacement | Usage of the Thomas-Ehrman Level Displacement formalism has been examined.
Mistakes and inconsistencies are found in several papers, being repeated in
subsequent works. Here, we present a complete formalism with a consistent set
of definitions. Full algorithms are made available, both as a {\tt FORTRAN}
source file and as a user-friendly Visual Basic executable tool, available for
download on the World Wide Web.
|
Smooth R\'enyi Entropy of Ergodic Quantum Information Sources | We prove that the average smooth Renyi entropy rate will approach the entropy
rate of a stationary, ergodic information source, which is equal to the Shannon
entropy rate for a classical information source and the von Neumann entropy
rate for a quantum information source.
|
The descent statistic on involutions is not log-concave | We establish a combinatorial connection between the sequence $(i_{n,k})$
counting the involutions on $n$ letters with $k$ descents and the sequence
$(a_{n,k})$ enumerating the semistandard Young tableaux on $n$ cells with $k$
symbols. This allows us to show that the sequences $(i_{n,k})$ are not
log-concave for some values of $n$, hence answering a conjecture due to F.
Brenti.
|
The Equivariant LS-Category of Polar Actions | We will provide a lower bound for the equivariant Lusternik-Schnirelmann
category of an arbitrary proper action in terms of the stratification by orbit
types, and an upper bound for proper polar actions in terms of the equivariant
Lusternik-Schnirelmann category of its generalized Weyl group. As an
application we reprove a theorem of Singhof that determines the classical
Lusternik-Schnirelmann category for U(n) and SU(n).
|
Cancelling Quadratic Divergences Without Supersymmetry | We construct a theory which has the same particle content as softly broken
minimal supersymmetric QED (MSQED) and is free of quadratic divergences up to
two loops. Also this theory is completely gauge invariant. It appears that
MSQED is not at all the only theory without these quadratic divergences. This
proves that there exist non supersymmetric theories in which there are no
quadratic divergences up to two loops.
|
Immersions of spheres and algebraically constructible functions | Let L be an algebraic set and let g : R^(n+1) \times L --> R^(2n) (n is even)
be a polynomial mapping such that for each l in L there is r(l)>0 such that the
mapping g_l = g(.,l) restricted to the sphere S^n(r) is an immersion for every
0<r<(l), so that the intersection number I(g_l|S^n(r)) is defined. Then the
function which maps l in L to I(g_l|S^n(r)) is algebraically constructible.
|
Spectroscopic Analyses of Massive Blue Stars (Galactic or Extragalactic) | We review recent advances in our understanding of massive stars through the
analysis of their spectra. Improvements in model atmospheres and analysis
methods are briefly discussed. Results obtained for stars in the Local Group
are compared and the present status of different open questions, like the
temperature scale of OB stars, the Wind Momentum-Luminosity Relation or the
stellar rotation, is outlined.
|
Remarks related to the paper of Rafael de la Madrid: "On the
inconsistency of the Bohm-Gadella theory with quantum mechanics", JPhysA 39,
No. 29, 9255-9268 (2006) | The paper contains critical comments to the paper mentioned in the title from
the mathematical point of view
|
Invariant forms, associated bundles and Calabi-Yau metrics | We develop a method, initially due to Salamon, to compute the space of
``invariant'' forms on an associated bundle X=P\times_G V, with a suitable
notion of invariance. We determine sufficient conditions for this space to be
d-closed. We apply our method to the construction of Calabi-Yau metrics on
TCP^1 and TCP^2.
|
Experimental Review on Pentaquarks | The experimental evidence for pentaquarks is reviewed and compared with the
experiments that do not see any sign of pentaquarks. This paper is based on a
lecture given at the 33rd ITEP Winter School of Physics in the beginning of
2005. Results obtained since then are summarized in the epilogue.
|
Some Phenomenologies of Unparticle Physics | Fermionic unparticles are introduced and their basic properties are
discussed. Some phenomenologies related are exploited, such as their effects on
charged Higgs boson decays and anomalous magnetic moments of leptons. Also, it
has been found that measurements of $B^0-\bar B^0$ mixing could yield
interesting constraints on couplings between unparticle operators and standard
model fields.
|
Non-LTE Analysis of Lyman-Line Observations of a Filament with SUMER | We present non-LTE diagnostics of the filament observed by SOHO/SUMER on May
27, 2005 in the whole Lyman series. The filament was situated close to the disk
center. The Ly_alpha observations were carried out with normal voltage of
detector A. The slit was placed at the central part of the detector -- outside
the Ly_alpha attenuator. Therefore, the observed profiles of this line could be
calibrated reliably.
|
Results on Dark Matter and beta beta decay modes by DAMA at Gran Sasso | DAMA is an observatory for rare processes and it is operative deep
underground at the Gran Sasso National Laboratory of the I.N.F.N. (LNGS). Here
some arguments will be presented on the investigation on dark matter particles
by annual modulation signature and on some of the realized double beta decay
searches.
|
Low frequency dispersive estimates for the wave equation in higher
dimensions | We prove dispersive estimates at low frequency in dimensions n greater or
equal to 4 for the wave equation for a very large class of real-valued
potentials, provided the zero is neither an eigenvalue nor a resonance.
|
Path integral quantization of scalar fluctuations above a kink | We quantize scalar fluctuations in 1+1 dimensions above a classical
background kink. The properties of the effective action for the corresponding
classical field are studied with an exact functional method, alternative to
exact Wilsonian renormalization, where the running parameter is a bare mass,
and the regulator of the quantum theory is fixed. We extend this approach, in
an appendix, to a Yukawa interaction in higher dimension.
|
The critical temperature for the BCS equation at weak coupling | For the BCS equation with local two-body interaction $\lambda V(x)$, we give
a rigorous analysis of the asymptotic behavior of the critical temperature as
$\lambda \to 0$. We derive necessary and sufficient conditions on $V(x)$ for
the existence of a non-trivial solution for all values of $\lambda>0$.
|
Fermion Masses and Mixings in GUTs with Non-Canonical U(1)_Y | We discuss fermion masses and mixings in models derived from orbifold GUTs
such that gauge coupling unification is achieved without low energy
supersymmetry by utilizing a non-canonical U(1)_Y. A gauged U(1)_X flavor
symmetry plays an essential role, and the Green-Schwarz mechanism is invoked in
anomaly cancellations. Models containing vector-like particles with masses
close to M_{GUT} are also discussed.
|
Generalized rotational hamiltonians from nonlinear angular momentum
algebras | Higgs algebras are used to construct rotational Hamiltonians. The
correspondence between the spectrum of a triaxial rotor and the spectrum of a
cubic Higgs algebra is demonstrated. It is shown that a suitable choice of the
parameters of the polynomial algebra allows for a precise identification of
rotational properties. The harmonic limit is obtained by a contraction of the
algebra, leading to a linear symmetry.
|
A class of generalized complex Hermite polynomials | A class of generalized complex polynomials of Hermite type, suggested by a
special magnetic Schrodinger operator, is introduced and some related basic
properties are discussed.
|
Two-loop QED corrections to Bhabha scattering | We obtain a simple relation between massless and massive scattering
amplitudes in gauge theories in the limit where all kinematic invariants are
large compared to particle masses. We use this relation to derive the two-loop
QED corrections to large-angle Bhabha scattering.
|
Comment on "Time Step Sensitivity of Nonlinear Atmospheric Models:
Numerical Convergence, Truncation Error Growth, and Ensemble Design" Teixeira
et al. (2007) | Comment on "Time Step Sensitivity of Nonlinear Atmospheric Models: Numerical
Convergence, Truncation Error Growth, and Ensemble Design" Teixeira et al.
|
Pseudoduality and Conserved Currents in Sigma Models | We discuss the current conservation laws in sigma models based on a compact
Lie groups of the same dimensionality and connected to each other via
pseudoduality transformations in two dimensions. We show that pseudoduality
transformations induce an infinite number of nonlocal conserved currents on the
pseudodual manifold.
|
A nearly optimal discrete query quantum algorithm for evaluating NAND
formulas | We present an O(\sqrt{N}) discrete query quantum algorithm for evaluating
balanced binary NAND formulas and an O(N^{{1/2}+O(\frac{1}{\sqrt{\log N}})})
discrete query quantum algorithm for evaluating arbitrary binary NAND formulas.
|
Bernstein-Szego Polynomials Associated with Root Systems | We introduce multivariate generalizations of the Bernstein-Szego polynomials,
which are associated to the root systems of the complex simple Lie algebras.
The multivariate polynomials in question generalize Macdonald's Hall-Littlewood
polynomials associated with root systems. For the root system of type A1
(corresponding to the Lie algebra SL (2;C)) the classic Bernstein-Szego
polynomials are recovered.
|
Statefinder Parameters for Five-Dimensional Cosmology | We study the statefinder parameter in the five-dimensional big bounce model,
and apply it to differentiate the attractor solutions of quintessence and
phantom field. It is found that the evolving trajectories of these two
attractor solutions in the statefinder parameters plane are quite different,
and that are different from the statefinder trajectories of other dark energy
models.
|
Periodicity of certain piecewise affine planar maps | We determine periodic and aperiodic points of certain piecewise affine maps
in the Euclidean plane. Using these maps, we prove for
$\lambda\in\{\frac{\pm1\pm\sqrt5}2,\pm\sqrt2,\pm\sqrt3\}$ that all integer
sequences $(a_k)_{k\in\mathbb Z}$ satisfying $0\le a_{k-1}+\lambda
a_k+a_{k+1}<1$ are periodic.
|
Optimal time evolution in (non)hermitian quantum mechanics | This paper has been withdrawn by the author
|
Holographic Chaplygin gas model | In this paper we consider a correspondence between the holographic dark
energy density and Chaplygin gas energy density in FRW universe. Then we
reconstruct the potential and the dynamics of the scalar field which describe
the Chaplygin cosmology.
|
Descent Relations in Cubic Superstring Field Theory | The descent relations between string field theory (SFT) vertices are
characteristic relations of the operator formulation of SFT and they provide
self-consistency of this theory. The descent relations <V_2|V_1> and <V_3|V_1>
in the NS fermionic string field theory in the kappa and discrete bases are
established. Different regularizations and schemes of calculations are
considered and relations between them are discussed.
|
Thermodynamics of system with density- and/or temperature-dependent mass
particles | The thermodynamics with medium effects expressed by the dispersion relation
of the temperature and density dependent particle mass is studied. Many
previous treatments have been reviewed. A new thermodynamical treatment based
on the equilibrium state is suggested. Employing the quark mass density- and
temperature-dependent model, the discrepancies between our treatment and others
are addressed.
|
Reconstruction Algebras of Type A | We introduce a new class of algebras, called reconstruction algebras, and
present some of their basic properties. These non-commutative rings dictate in
every way the process of resolving the Cohen-Macaulay singularities C^2/G where
G is a finite small cyclic subgroup of GL(2,C).
|
On The Spectrum of Yang-Mills Theory in 2+1 Dimensions, Analytically | We review our recent work on the glueball spectrum of pure Yang-Mills theory
in 2+1 dimensions. The calculations make use of Karabali-Nair corner variables
in the Hamiltonian formalism, and involve a determination of the leading form
of the ground-state wavefunctional.
|
A weighted graph problem from commutative algebra | We give an especially simple proof of a theorem in graph theory that forms
the key part of the solution to a problem in commutative algebra, on how to
characterize the integral closure of a polynomial ring generated by quadratic
monomials.
|
Demazure embeddings are smooth | We prove Brion's conjecture stating that the closure of the orbit of a
self-normalizing spherical subalgebra in the corresponding Grassmanian is
smooth
|
Constrained flow around a magnetic obstacle | Many practical applications exploit an external local magnetic field --
magnetic obstacle -- as an essential part of their constructions. Recently, it
has been demonstrated that the flow of an electrically conducting fluid
influenced by an external field can show several kinds of recirculation. The
present paper reports a 3D numerical study whose some results are compared with
an experiment about such a flow in a rectangular duct.
|
Maximal C*-algebras of quotients and injective envelopes of C*-algebras | A new C*-enlargement of a C*-algebra $A$ nested between the local multiplier
algebra $M_{\text{loc}}(A)$ of $A$ and its injective envelope $I(A)$ is
introduced. Various aspects of this maximal C*-algebra of quotients,
$Q_{\text{max}}(A)$, are studied, notably in the setting of AW*-algebras. As a
by-product we obtain a new example of a type I C*-algebra $A$ such that
$M_{\text{loc}}(M_{\text{loc}}(A))\ne M_{\text{loc}}(A)$.
|
Nuclear p_t broadening at HERMES | The first direct measurement of p_t-broadening effects in cold nuclear matter
has been studied as a function of several kinematic variables for different
hadron types. The data have been accumulated by the HERMES experiment at DESY,
in which the HERA 27.6 GeV lepton beam scattered off several nuclear gas
targets.
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Existence and Number of Solutions of Diophantine Quadratic Equations
with Two Unknowns in $Z$ and $N$ | In this short note we study the existence and number of solutions in the set
of integers ($Z$) and in the set of natural numbers ($N$) of Diopahntine
Equations of second degree with two variables of the general form
$ax^2-by^2=c$.
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Codazzi spinors and globally hyperbolic manifolds with special holonomy | In this paper we examine the structure of Riemannian manifolds with a special
kind of Codazzi tensors. We use them to construct globally hyperbolic
Lorentzian manifolds with complete Cauchy hypersurfaces for any weakly
irreducible holonomy representation with parallel spinors, i.e. with a holonomy
group which is a semidirect product between $\R^{n-2}$ and one of $\1, SU(k),
Sp(1), G_2$ and $Spin(7)$.
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Torsion units in integral group ring of the Mathieu simple group M22 | We investigate the possible character values of torsion units of the
normalized unit group of the integral group ring of Mathieu sporadic group
$M_{22}$. We confirm the Kimmerle conjecture on prime graphs for this group and
specify the partial augmentations for possible counterexamples to the stronger
Zassenhaus conjecture.
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The General Form Of Cyclic Orthonormal Generators In R^N | In this paper we give a definition of cyclic orthonormal generators (cogs) in
R^N. We give a general canonical form for their expression. Further, we give an
explicit formula for computing the canonical form of any given cog.
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Lattice QCD thermodynamics with Wilson quarks | We review studies of QCD thermodynamics by lattice QCD simulations with
dynamical Wilson quarks. After explaining the basic properties of QCD with
Wilson quarks at finite temperature including the phase structure and the
scaling properties around the chiral phase transition, we discuss the critical
temperature, the equation of state and heavy-quark free energies.
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Generalizing the notion of Koszul algebra | We introduce a generalization of the notion of a Koszul algebra, which
includes graded algebras with relations in different degrees, and we establish
some of the basic properties of these algebras. This class is closed under
twists, twisted tensor products, regular central extensions and Ore extensions.
We explore the monomial algebras in this class and we include some well-known
examples of algebras that fall into this class.
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Gorenstein algebras and Hochschild cohomology | For homomorphism K-->S of commutative rings, where K is Gorenstein and S is
essentially of finite type and flat as a K-module, the property that all
non-trivial fiber rings of K-->S are Gorenstein is characterized in terms of
properties of the cohomology modules Ext_n^{S\otimes_KS}S{S\otimes_KS}.
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A new proof of the Beez-Cartan theorem | This paper has been withdrawn by the author.
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On the limits of surface fractal behaviour in silica. A virtual
adsorbates simulation | A computer simulation technique, suited to replicate real adsorption
experiments, was applied to pure simulated silica in order to gain insight into
the fractal regime of its surface. The previously reported experimental fractal
dimension was closely approached and the hitherto uncharted lower limit of
fractal surface behaviour is reported herein.
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On the smoothness of H\"older-doubling measures | In this paper we consider the question of whether the doubling character of a
measure supported on a subset of $\RR^m$ determines the regularity of its
support (in a classical sense). This problem was studied by David, Kenig and
Toro for codimension 1 sets under the assumption that the support be flat. Here
we study the higher codimension case and remove the flatness hypothesis.
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Graphene: A Pseudochiral Fermi Liquid | Doped graphene sheets are pseudochiral two-dimensional Fermi liquids with
abnormal electron-electron interaction physics. We address graphene's Fermi
liquid properties quantitatively using a microscopic random-phase-approximation
theory and comment on the importance of using exchange-correlation potentials
based on the properties of a chiral two-dimensional electron gas in
density-functional-theory applications to graphene nanostructures.
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