Fragmentation of jets containing a prompt J$/\psi$ meson in PbPb and pp collisions at $\sqrt{s_\mathrm{NN}} =$ 5.02 TeV

TL;DR

This study investigates how the production of prompt J/ψ mesons within jets is affected by the quark-gluon plasma in PbPb collisions at 5.02 TeV, revealing a z-dependent suppression pattern.

Contribution

It provides the first measurement of J/ψ-containing jet fragmentation functions and their nuclear modification in heavy-ion collisions at the LHC.

Findings

J/ψ yield suppression depends on the fragmentation variable z.

The nuclear modification factor R_AA varies with z, indicating medium effects.

Results suggest interaction of J/ψ with the quark-gluon plasma depends on fragmentation.

Abstract

Jets containing a prompt J$/\psi$ meson are studied in lead-lead collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV, using the CMS detector at the LHC. Jets are selected to be in the transverse momentum range of 30 $\lt$ $p_\mathrm{T}$ $\lt$ 40 GeV. The J$/\psi$ yield in these jets is evaluated as a function of the jet fragmentation variable $z$, the ratio of the J$/\psi$ $p_\mathrm{T} $ to the jet $p_\mathrm{T}$. The nuclear modification factor, $R_\mathrm{AA}$, is then derived by comparing the yield in lead-lead collisions to the corresponding expectation based on proton-proton data, at the same nucleon-nucleon center-of-mass energy. The suppression of the J$/\psi$ yield shows a dependence on $z$, indicating that the interaction of the J$/\psi$ with the quark-gluon plasma formed in heavy ion collisions depends on the fragmentation that gives rise to the J$/\psi$ meson.