Medium Modifications and Production of Charmonia at LHC

TL;DR

This paper applies a transport model constrained by lattice QCD to predict charmonium production and suppression in Pb-Pb collisions at the LHC, highlighting the impact of charm cross section uncertainties and non-equilibrium effects.

Contribution

It introduces a transport approach incorporating lattice QCD spectral data to predict charmonium yields at LHC energies, accounting for suppression and regeneration mechanisms.

Findings

Predicted J/ψ yields depend on charm cross section and shadowing effects.

Charm quark non-equilibrium reduces regeneration yield.

Model successfully describes SPS and RHIC data.

Abstract

A previously constructed transport approach to calculate the evolution of quarkonium yields and spectra in heavy-ion collisions is applied to Pb-Pb($\sqrt{s}$=2.76\,ATeV) collisions at the Large Hadron Collider (LHC). In this approach spectral properties of charmonia are constrained by euclidean correlators from thermal lattice QCD and subsequently implemented into a Boltzmann equation accounting for both suppression and regeneration reactions. Based on a fair description of SPS and RHIC data, we provide predictions for the centrality dependence of $J/\psi$ yields at LHC. The main uncertainty is associated with the input charm cross section, in particular its hitherto unknown reduction due to shadowing in nuclear collisions. Incomplete charm-quark thermalization and non-equilibrium in charmonium chemistry entail a marked reduction of the regeneration yield compared to the statistical equilibrium limit.