--- license: mit tags: - physics pretty_name: JetClass-II size_categories: - 100B The dataset consists of three major parts based on the jet origin and its substructure: 1. **`Res2P`**: Generic \\(X\\) → 2 prong resonant jets. 1. **`Res34P`**: Generic \\(X\\) → 3 or 4 prong resonant jets. 1. **`QCD`**: Jets from QCD multijet background. Each part is further subdivided into detailed categories, indicating which partons, leptons, or combinations thereof initiated the jet. ![image/png](https://cdn-uploads.huggingface.co/production/uploads/628ede0689851fc47c026d50/JXP-j8oksJpFx9KqjKTzM.png) The three major parts (**`Res2P`**, **`Res34P`**, and **`QCD`**) are separately packed and can be downloaded individually for ease of use. The sizes of the training sets are 20M, 86M, and 28M entries, respectively. The dataset also includes validation and test sets, with the sizes for training/validation/test following a 4:1:1 ratio. Every 100k entries (jets) are stored in a Parquet file. A complete view of the JetClass-II data files is shown in the table below. | Type | File name range | File number | total entries | | --- | --- | --- | --- | | **`Res2P`, train** | `Res2P_0000.parquet`—`Res2P_0199.parquet` | **200** | **20M** | | `Res2P`, val | `Res2P_0200.parquet`—`Res2P_0249.parquet` | 50 | 5M | | `Res2P`, test | `Res2P_0250.parquet`—`Res2P_0299.parquet` | 50 | 5M | | **`Res34P`, train** | `Res34P_0000.parquet`—`Res34P_0859.parquet` | **860** | **86M** | | `Res34P`, val | `Res34P_0860.parquet`—`Res34P_1074.parquet` | 215 | 21.5M | | `Res34P`, test | `Res34P_1075.parquet`—`Res34P_1289.parquet` | 215 | 21.5M | | **`QCD`, train** | `QCD_0000.parquet`—`QCD_0279.parquet` | **280** | **28M** | | `QCD`, val | `QCD_0280.parquet`—`QCD_0349.parquet` | 70 | 7M | | `QCD`, test | `QCD_0350.parquet`—`QCD_0419.parquet` | 70 | 7M | - **License:** MIT ### Dataset Demo Use [[Colab]](https://colab.research.google.com/github/jet-universe/sophon/blob/main/notebooks/Interacting_with_JetClassII_and_Sophon.ipynb) to inspect and visualize data in JetClass-II. This demo will showcase visualizations of jets, annotated with the top 5 probability scores as interpreted by the [Sophon model, the first application on JetClass-II](https://github.com/jet-universe/sophon). ![image/png](https://cdn-uploads.huggingface.co/production/uploads/628ede0689851fc47c026d50/jcXqSHqwSqO6ETIsqntIU.png) ### Dataset Downloads To facilitate downloading, the HTTP links for all data files are provided in [`filelist.txt`](filelist.txt). ### Dataset Sources - **Repository:** https://github.com/jet-universe/sophon - **Paper:** https://arxiv.org/abs/2405.12972 - **Demo:** https://colab.research.google.com/github/jet-universe/sophon/blob/main/notebooks/Interacting_with_JetClassII_and_Sophon.ipynb ## Uses 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). ## Dataset Structure 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 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\\). 4. The subsequent decay products of tau leptons in case (iii). 5. The partons ( \\(p_\mathrm{T}\\) > 5 GeV) matched within a QCD jet. | Variable | Type | Description | Exists in JetClass? | | --- | --- | --- | --- | | **For jet constituent particles** | | | | | `part_px` | vector\ | particle's \\(p_x\\) | ✔️ | `part_py` | vector\ | particle's \\(p_y\\) | ✔️ | `part_pz` | vector\ | particle's \\(p_z\\) | ✔️ | `part_energy` | vector\ | particle's energy | ✔️ | `part_deta` | vector\ | difference in pseudorapidity \\(\eta\\) between the particle and the jet axis | ✔️ | `part_dphi` | vector\ | difference in azimuthal angle \\(\phi\\) between the particle and the jet axis | ✔️ | `part_d0val` | vector\ | particle's transverse impact parameter value \\(d_0\\), in mm | ✔️ | `part_d0err` | vector\ | error of the particle's transverse impact parameter \\(\sigma_{d_0}\\), in mm | ✔️ | `part_dzval` | vector\ | particle's longitudinal impact parameter value \\(d_z\\), in mm | ✔️ | `part_dzerr` | vector\ | error of the particle's longitudinal impact parameter \\(\sigma_{d_z}\\), in mm | ✔️ | `part_charge` | vector\ | particle's electric charge | ✔️ | `part_isElectron` | vector\ | if the particle is an electron (`abs(pid)==11`) | ✔️ | `part_isMuon` | vector\ | if the particle is an muon (`abs(pid)==13`) | ✔️ | `part_isPhoton` | vector\ | if the particle is an photon (`pid==22`) | ✔️ | `part_isChargedHadron` | vector\ | if the particle is a charged hadron (`charge!=0 && !isElectron && !isMuon`) | ✔️ | `part_isNeutralHadron` | vector\ | if the particle is a neutral hadron (`charge==0 && !isPhoton`) | ✔️ | **For jets** | | | | | `jet_pt` | float | jet's transverse momentum \\(p_\mathrm{T}\\) | ✔️ | `jet_eta` | float | jet's pseudorapidity \\(\eta\\) | ✔️ | `jet_phi` | float | jet's azimuthal angle \\(\phi\\) | ✔️ | `jet_energy` | float | jet's energy | ✔️ | `jet_sdmass` | float | jet's soft-drop mass | ✔️ | `jet_nparticles` | int32_t | number of jet constituent particles | ✔️ | `jet_tau1` | float | jet's \\(N\\)-subjettiness variable \\(\tau_1\\) | ✔️ | `jet_tau2` | float | jet's \\(N\\)-subjettiness variable \\(\tau_2\\) | ✔️ | `jet_tau3` | float | jet's \\(N\\)-subjettiness variable \\(\tau_3\\) | ✔️ | `jet_tau4` | float | jet's \\(N\\)-subjettiness variable \\(\tau_4\\) | ✔️ | `jet_label` | int32_t | jet's label index in JetClass-II, detailed in the above table | 🆕 | **For GEN-jet constituent particles** (if a GEN-jet is found matched to a jet) | | | | | `genpart_px` | vector\ | particle's \\(p_x\\) | 🆕 | `genpart_py` | vector\ | particle's \\(p_y\\) | 🆕 | `genpart_pz` | vector\ | particle's \\(p_z\\) | 🆕 | `genpart_energy` | vector\ | particle's energy | 🆕 | `genpart_jet_deta` | vector\ | difference in pseudorapidity \\(\eta\\) between the particle and the jet (not the GEN-jet) axis | 🆕 | `genpart_jet_dphi` | vector\ | difference in azimuthal angle \\(\phi\\) between the particle and the jet (not the GEN-jet) axis | 🆕 | `genpart_x` | vector\ | \\(x\\) coordinate of the particle's production vertex, in mm | 🆕 | `genpart_y` | vector\ | \\(y\\) coordinate of the particle's production vertex, in mm | 🆕 | `genpart_z` | vector\ | \\(z\\) coordinate of the particle's production vertex, in mm | 🆕 | `genpart_t` | vector\ | \\(t\\) coordinate of the particle's production vertex, in mm/c | 🆕 | `genpart_pid` | vector\ | particle's PDGID | 🆕 | **For GEN-jets** (if matched to a jet) | | | | | `genjet_pt` | float | GEN-jet's transverse momentum \\(p_\mathrm{T}\\) | 🆕 | `genjet_eta` | float | GEN-jet's pseudorapidity \\(\eta\\) | 🆕 | `genjet_phi` | float | GEN-jet's azimuthal angle \\(\phi\\) | 🆕 | `genjet_energy` | float | GEN-jet's energy | 🆕 | `genjet_sdmass` | float | GEN-jet's soft-drop mass | 🆕 | `genjet_nparticles` | int32_t | number of GEN-jet constituent particles | 🆕 | **For selected truth particles** | | | | | `aux_genpart_pt` | vector\ | selected truth particles' \\(p_\mathrm{T}\\) | ✔️ (different rules to select truth particles) | `aux_genpart_eta` | vector\ | selected truth particles' \\(\eta\\) | ✔️ (different rules to select truth particles) | `aux_genpart_phi` | vector\ | selected truth particles' \\(\phi\\) | ✔️ (different rules to select truth particles) | `aux_genpart_mass` | vector\ | selected truth particles' mass | ✔️ (different rules to select truth particles) | `aux_genpart_pid` | vector\ | selected truth particles' PDGID | 🆕 | `aux_genpart_isResX` | vector\ | if the particle is the initial resonance \\(X\\) | 🆕 | `aux_genpart_isResY` | vector\ | if the particle is the secondary resonance \\(Y\\) | 🆕 | `aux_genpart_isResDecayProd` | vector\ | if the particle is the direct decay product (parton and lepton) from \\(X\\) and \\(Y\\) | 🆕 | `aux_genpart_isTauDecayProd` | vector\ | if the particle is the subsequent decay product of tau leptons | 🆕 | `aux_genpart_isQcdParton` | vector\ | if the particle is the parton with \\(p_\mathrm{T}\\) > 5 GeV stored in the QCD jet case | 🆕 ## Dataset Creation The dataset is generated using MadGraph + Pythia + Delphes. During the Delphes (fast simulation) step, the pileup (PU) effect, with an average of 50 PU interactions, is emulated to mimic the realistic LHC collision environment. The PUPPI algorithm is then applied to remove the PU, correcting the E-flow objects used to cluster jets. This distinguishes it from the original JetClass dataset. The Delphes card can be found in the [`jetclass2-generation`](https://github.com/jet-universe/jetclass2_generation) repository. The complete generation script (the one-stop MadGraph + Pythia + Delphes production) and the n-tuplizer script are provided in the [`jetclass2-generation`](https://github.com/jet-universe/jetclass2_generation) repository to facilitate reproducibility. Truth particles are selected using [Insert criteria]. GEN-jets are clustered truth particles matched to jets using [Insert criteria]. ## Citation If you use the JetClass-II dataset, please cite: **BibTeX:** ```bibtex @article{Li:2024htp, author = "Li, Congqiao and Agapitos, Antonios and Drews, Jovin and Duarte, Javier and Fu, Dawei and Gao, Leyun and Kansal, Raghav and Kasieczka, Gregor and Moureaux, Louis and Qu, Huilin and Suarez, Cristina Mantilla and Li, Qiang", title = "{Accelerating Resonance Searches via Signature-Oriented Pre-training}", eprint = "2405.12972", archivePrefix = "arXiv", primaryClass = "hep-ph", month = "5", year = "2024" } ``` ## Glossary 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 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**: The particles (reconstructed hadrons, electrons, muons, or photons) that form the jet after clustering. **GEN-jet**: A generator-level jet, reconstructed from a list of stable truth particles in a simulation. **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}\\)**: The component of the momentum of a particle (or jet) that is transverse (i.e., perpendicular) to the beam axis. **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**: The distance of the closest approach of the track to the collision point. **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] ## Dataset Card Authors and Contacts @jmgduarte, @colizz