Update README.md

README.md

@@ -71,7 +71,7 @@ To facilitate downloading, the HTTP links for all data files are provided in [`f
 
 <!-- Address questions around how the dataset is intended to be used. -->
 
-1. This dataset can be used to train models for a variety of jet-related tasks, such as jet classification, jet property regression, and jet generation or reconstruction.
+1. This dataset can be used to train models for various jet-related tasks, such as jet classification, jet property regression, and jet generation or reconstruction.
 1. The dataset's extensive phase space coverage and high statistics enable model developers to focus on specific regions of interest, or work with the entire dataset, enabling the creation of specialized models for particular phase spaces or pre-training a more general model.
 1. The dataset contains detailed low-level information to support customized model training strategies, including kinematic features, particle IDs, and trajectory displacement information for both jet constituent particles and relevant generator-level particles (see details in the next section).
 
@@ -81,9 +81,9 @@ The JetClass-II dataset includes the following variables:
 
 1. `part_*`: Features for jet constituent particles (i.e., E-flow objects in Delphes).
 2. `jet_*`: Features for jets. A specific variable is `jet_label`, which indicates the label in 188 classes.
-3. `genpart_*`: Features for generator-level jet (GEN-jet) constituent particles. The GEN-jet is clustered from the stable particles generated by Pythia, excluding neutrinos, using the same clustering configuration. The GEN-jets are matched with jets based on angular separation. The entry is left empty if no matched GEN-jet is found.
-4. `genjet_*`: Jet-level features for the matched GEN-jet.
-5. `aux_genpart_*`: Auxiliary variables storing features of selected truth particles. Five types of particles are chosen if they are valid:
+3. `genpart_*`: Features for generator-level jet (GEN-jet) constituent particles. The GEN-jet is clustered from the stable particles generated by Pythia, excluding neutrinos, using the same clustering configuration. The GEN-jets are matched with jets based on the pseudoangular separation \\(\Delta R\\). Jets, ordered by decreasing \\(p_\mathrm{T}\\), are paired with the closest unmatched GEN-jet. If no matched GEN-jet is found, the entry is left empty, which occurs in only 0.2–0.8% of cases.
+5. `genjet_*`: Jet-level features for the matched GEN-jet.
+6. `aux_genpart_*`: Auxiliary variables storing features of selected truth particles. Five types of particles are chosen if they are valid:
     1. The initial resonance \\(X\\) (in both 2-prong and 3/4-prong resonance cases).
     2. The two secondary resonances \\(Y\\) produced by \\(X\\) ( \\(X \to Y_1Y_2\\) ) in the 3/4-prong resonance case.
     3. The direct decay products (partons and leptons) from \\(X\\) and \\(Y\\).
@@ -195,23 +195,24 @@ If you use the JetClass-II dataset, please cite:
 
 A good resource is the CERN Open Data Portal Glossary: https://opendata.cern.ch/search?q=&f=type%3AGlossary&l=list&order=asc&p=1&s=10&sort=title
 
-**Jet**: A jet is a shower of hadrons, which originate from a quark or a gluon, clustered together after being produced in particle collisions.
+**Jet**: A jet is a shower of hadrons, which originate from quarks or gluons, clustered together after being produced in particle collisions. A large-radius jet is clustered using a larger radius parameter \\(R\\) (0.8 in this dataset) and may result from a collection of nearby quarks, gluons, and other particles.
 
-**Constituent particle**:
+**Constituent particle**: The particles (reconstructed hadrons, electrons, muons, or photons) that form the jet after clustering.
 
-**GEN-Jet**:
+**GEN-jet**: A generator-level jet, reconstructed from a list of stable truth particles in a simulation.
 
-**Truth particle**:
+**Truth particle**: Particles produced during a collision in a simulation. Initial truth particles are directly generated in the hard collision process, but they may undergo decays, intermediate emissions, and parton showering to produce the stable particles ultimately observed by the detector. These stable particles are used to cluster GEN-jets.
 
 **Pseudorapidity \\(\eta\\)**: The pseudorapidity \\(\eta\\) is a coordinate that describes the angle of a particle (or jet) produced in an event relative to the beam axis. It is calculated as  \\(\eta = - \ln \left ( \tan \frac{\theta}{2} \right )\\), with \\(\theta\\) the angle between the three-momentum and the beam axis. \\(\eta=0\\) means the produced particle/jet is perpendicular to the beam axis, while a higher pseudorapidity means it is closer to the beam.
 
-**Transverse momentum \\(\p_\mathrm{T}\\)**:
+**Transverse momentum \\(p_\mathrm{T}\\)**: The component of the momentum of a particle (or jet) that is transverse (i.e., perpendicular) to the beam axis.
 
-**Pseudoangular distance \\(\Delta R\\)**:
+**Pseudoangular distance \\(\Delta R\\)**: \\(\Delta R(a,\,b) = \sqrt{(\eta_a - \eta_b)^2 + (\phi_a - \phi_b)^2}\\), where \\(\eta\;(\phi)\\) is the pseudorapidity
+(azimuthal angle) of the momentum of a particle or a jet. A particle is considered matched to the jet if \\(\Delta R\mathrm{(particle,\;jet\,axis)} > R_0\\), where \\(R_0\\) is the jet radius parameter.
 
-**Impact parameter**:
+**Impact parameter**: The distance of the closest approach of the track to the collision point.
 
-**PDG particle ID**: 
+**Particle's PDGID**: A unique identifier assigned to each particle type by the [Particle Data Group (PDG)](https://pdg.lbl.gov/). The full PDGID table can be accessed [here](https://pdg.lbl.gov/2024/reviews/rpp2024-rev-monte-carlo-numbering.pdf).
 
 [More Information Needed]