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

Understand

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.