Inclusive, prompt and non-prompt J/ψ identification in proton-proton collisions at the Large Hadron Collider using machine learning
arxiv(2023)
摘要
Studies related to J/ψ meson, a bound state of charm and anti-charm
quarks (cc̅), in heavy-ion collisions, provide genuine testing grounds
for the theory of strong interaction, quantum chromodynamics (QCD). To better
understand the underlying production mechanism, cold nuclear matter effects,
and influence from the quark-gluon plasma, baseline measurements are also
performed in proton-proton (pp) and proton-nucleus (p–A) collisions. The
inclusive J/ψ measurement has contributions from both prompt and
non-prompt productions. The prompt J/ψ is produced directly from the
hadronic interactions or via feed-down from directly produced higher charmonium
states, whereas non-prompt J/ψ comes from the decay of beauty
hadrons. In experiments, J/ψ is reconstructed through its
electromagnetic decays to lepton pairs, in either e^++e^- or
μ^++μ^- decay channels. In this work, for the first time, machine
learning techniques are implemented to separate the prompt and non-prompt
dimuon pairs from the background to obtain a better identification of the
J/ψ signal for different production modes. The study has been
performed in pp collisions at √(s) = 7 and 13 TeV simulated using
PYTHIA8. Machine learning models such as XGBoost and LightGBM are explored. The
models could achieve up to 99% prediction accuracy. The transverse momentum
(p_ T) and rapidity (y) differential measurements of inclusive,
prompt, and non-prompt J/ψ, its multiplicity dependence, and the
p_ T dependence of fraction of non-prompt J/ψ (f_ B)
are shown. These results are compared to experimental findings wherever
possible.
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