Charmonium production from nonequilibrium charm and anticharm quarks in quark-gluon plasma

TL;DR

This paper investigates how nonequilibrium charm and anticharm quark distributions affect charmonium production in quark-gluon plasma, revealing suppression effects and validating relaxation time approximations.

Contribution

It introduces a Tsallis distribution approach to model nonequilibrium charm quarks and computes the impact on charmonium production rates up to next-to-leading order in QCD.

Findings

Nonequilibrium charm quarks suppress charmonium production.

Suppression factor aligns with relaxation time estimates.

Results highlight importance of nonequilibrium effects in QGP.

Abstract

Parameterizing the charm and anticharm quark momentum distributions by the Tsallis distribution, we study the nonequilibrium effect on the charmonium production rate in a quark-gluon plasma up to the next-to-leading order in perturbative QCD. We find that nonequilibrium charm and anticharm quarks suppress the charmonium production rate compared to that from equilibrated ones. We further show that the suppression factor calculated with the charm quark relaxation time, which has been frequently used in the literature, is close to our results.