Cold Nuclear Matter Effects on jpsi Production with Extrinsic pT at $\sqrt{s_{NN}}=5.5\mathrm{~TeV}$ at the LHC

TL;DR

This paper evaluates Cold Nuclear Matter effects, including gluon shadowing and nuclear absorption, on J/psi production at LHC energies, revealing significant suppression influenced by rapidity and partonic processes.

Contribution

It employs a complete kinematic description of the g+g→J/psi+g process to analyze CNM effects at 5.5 TeV, extending previous models with improved accuracy.

Findings

Large J/psi suppression due to gluon shadowing

Strong rapidity dependence of CNM effects

Potential partial compensation of recombination effects

Abstract

Taking into account the gluon shadowing and the $J/\psi$ nuclear absorption, we evaluate the Cold Nuclear Matter (CNM) effects on $J/\psi$ production in $p$Pb and PbPb collisions at the design LHC energy for PbPb collisions, $\sqrt{s_{NN}}=5.5$ TeV. In view of the good agreement between the yield prediction using the LO CSM and the ALICE data at 7 TeV, we employ the latter model to use a complete description of the kinematics of the underlying $2 \rightarrow 2$ partonic process, namely $g + g \rightarrow J/\psi + g$. We observe a large $J/\psi$ suppression in $p$Pb and PbPb collisions due to the strong shadowing of the gluon distribution in the lead ion at the corresponding gluon momentum fractions. This suppression from CNM effects has a strong rapidity dependence which may compensate, partially or completely, that of of the predicted charm recombination in PbPb collisions.