Top quark pair production with fully hadronic final states at the LHC

This public dataset was used to develop HyPER (Hypergraph for Particle Event Reconstruction).

HyPER uses blended graph-hypergraph representation learning to reconstruct short-lived particles produced at the LHC.

Production

Software

Matrix Elements (ME) and NLO Matching: MadGraph5_aMC@NLO (v2.9.16 LTS) at \(\sqrt{s}=13\) TeV.

Parton Distribution Function (PDF): NNPDF3.0nlo from LHAPDF6 (v6.3.0).

Parton Shower: PYTHIA8 (v8.306).

Detector: Delphes (v3.5.0), ATLAS detector geometry.

Jet Reconstruction: Fastjet (v3.4.0), anti-\(k_t\) algorithm with \(R=0.4\)

Jet truth matching

Jets are matched to their originating particles using the \(\Delta R\) truth matching scheme. If the angular distance between a particle and its nearest jet satisfies \(\Delta R < 0.4\), then the jet is matched to the particle. We use the following integer labels in jet_truthmatch: 0, 1, 2, 3, 4, 5, 6 ("not matched", b1, W1q1, W1q2, b2, W2q1, W2q2).

Event selections

Events contain at least 6 jets, of which 2 or more are b-tagged.

At least one identifiable W boson (two jets are matched to the decays of a W boson).

Reconstructed jets have a minimum \(p_T\) of 25 GeV and an absolute pseudorapidity \(|\eta|<2.5\).

Dataset Information

Training
Validation
Testing
Size-reduced

Dataset name
ttbar_train.root
ttbar_val.root
ttbar_test.root
ttbar_reduced.root

Internal ID
762705-{0-53}
762705-{54-56}
762705-{57-59}
Sampled from ttbar_train.root

Number of events*
54M
3M
3M
3M

Pass selections
7,921,299
439,692
440,069
439,598

Both tops matched
2,116,231
117,487
116,960
117,812

Max number of jets
20
20
18
20

*Only events that have passed selections are saved.

Dataset structure

Events are saved in ROOT files. They have the following structure:

- Delphes
---- njet // Int; Number or jets
---- nbTagged // Int; Number of b-tagged jets
---- allMatchedEvent // Int; Event is fully matched (1 or 0)
---- leastOneMatchedW // Int; Event contains at least one matched W (1 or 0)
---- jet_pt // vector; Transverse momentum of jets
---- jet_eta // vector; Pseudo-rapidity of jets
---- jet_phi // vector; Azimuthal angle of jets
---- jet_e // vector; Energy of jets
---- jet_m // vector; Invariant mass of jets
---- jet_bTag // vector; B-tagging status of jets---- jet_truthmatch // vector; DeltaR jet truth matching results
---- particle_pid // vector; Particle PDGID
---- particle_pt // vector; Transverse momentum of particles
---- particle_eta // vector; Pseudo-rapidity of particles
---- particle_phi // vector; Azimuthal angle of particles
---- particle_m // vector; Invariant mass of particles

jet_* branches containing information on the final-state jets. Information on short-lived particles is obtained from generator history are saved to particle_* branches.