Differential studies of inclusive J/$\psi$ and $\psi$(2S) production at forward rapidity in Pb-Pb collisions at $\mathbf{\sqrt{{\textit s}_{_{NN}}}}$ = 2.76 TeV

TL;DR

This paper reports on the measurement of J/ψ and ψ(2S) production in Pb-Pb collisions at 2.76 TeV, analyzing suppression patterns and their dependence on collision centrality, transverse momentum, and rapidity, to understand quarkonium behavior in quark-gluon plasma.

Contribution

It provides the first detailed analysis of inclusive J/ψ and ψ(2S) production at forward rapidity in Pb-Pb collisions at LHC energy, including suppression patterns and their theoretical implications.

Findings

J/ψ suppression varies with centrality, pT, and rapidity.

The interplay of color screening and recombination affects J/ψ production.

ψ(2S) suppression is quantified relative to J/ψ in different collision systems.

Abstract

The production of J/$\psi$ and $\psi(2S)$ was measured with the ALICE detector in Pb-Pb collisions at the LHC. The measurement was performed at forward rapidity ($2.5 < y < 4 $) down to zero transverse momentum ($p_{\rm T}$) in the dimuon decay channel. Inclusive J/$\psi$ yields were extracted in different centrality classes and the centrality dependence of the average $p_{\rm T}$ is presented. The J/$\psi$ suppression, quantified with the nuclear modification factor ($R_{\rm AA}$), was studied as a function of centrality, transverse momentum and rapidity. Comparisons with similar measurements at lower collision energy and theoretical models indicate that the J/$\psi$ production is the result of an interplay between color screening and recombination mechanisms in a deconfined partonic medium, or at its hadronization. Results on the $\psi(2S)$ suppression are provided via the ratio of $\psi(2S)$ over J/$\psi$ measured in pp and Pb-Pb collisions.