Study of $J/\psi$ production and cold nuclear matter effects in $p$Pb collisions at $\sqrt{s_{NN}}=5 \mathrm{TeV}$

TL;DR

This paper investigates $J/$ meson production and cold nuclear matter effects in proton-lead collisions at 5 TeV, revealing suppression patterns and providing new insights into nuclear modifications relevant for quark-gluon plasma studies.

Contribution

It presents the first separate measurements of nuclear modification factors and production ratios for prompt and $b$-hadron decay $J/$ mesons in $p$Pb collisions at 5 TeV.

Findings

Prompt $J/$ mesons are suppressed at large rapidity.

$J/$ from $b$-hadron decays are less suppressed.

Results agree with theoretical predictions.

Abstract

The production of $J/\psi$ mesons with rapidity $1.5<y<4.0$ or $-5.0<y<-2.5$ and transverse momentum $p_\mathrm{T}<14 \mathrm{GeV}/c$ is studied with the LHCb detector in proton-lead collisions at a nucleon-nucleon centre-of-mass energy $\sqrt{s_{NN}}=5 \mathrm{TeV}$. The analysis is based on a data sample corresponding to an integrated luminosity of about $1.6 \mathrm{nb}^{-1}$. For the first time the nuclear modification factor and forward-backward production ratio are determined separately for prompt $J/\psi$ mesons and $J/\psi$ from $b$-hadron decays. Clear suppression of prompt $J/\psi$ production with respect to proton-proton collisions at large rapidity is observed, while the production of $J/\psi$ from $b$-hadron decays is less suppressed. These results show good agreement with available theoretical predictions. The measurement shows that cold nuclear matter effects are important for interpretations of the related quark-gluon plasma signatures in heavy-ion collisions.