Recombinant Charmonium in strongly coupled Quark-Gluon Plasma

TL;DR

This paper models the production of J/psi particles in heavy-ion collisions, highlighting the significant role of recombination of charm quarks from different sources, which improves agreement with experimental data.

Contribution

It introduces a detailed Langevin model incorporating recombination effects, quantifying their impact on J/psi yields in heavy-ion collisions.

Findings

Recombinant J/psi accounts for 30-50% of yields in central collisions.

Including recombination aligns model predictions with RHIC experimental data.

Recombination notably affects the differential p_t distributions of J/psi.

Abstract

We update our previous work of a Langevin-with-interaction model for charmonium in heavy-ion collisions, by considering the effect due to recombination. We determine the contribution to J/psi yields from charm-anticharm pairs whose constituent quarks originate from two different hard processes. Like the surviving J/psi states, the recombinant J/psi also undergo both a stochastic interaction, determined by a hydrodynamical simulation of the heavy-ion collision, and an interaction determined by the heavy quark-antiquark potentials measured on the lattice for appropriate temperatures. From the results of these simulations, we determine both the direct and the recombinant contribution to the J/psi yields for RHIC conditions, and find that for central collisions, between 30% and 50% of the J/psi yield is due to recombinant production. We compare our results with other models and look for how the recombinant contribution differs from the surviving contribution in the differential p_t yields. Including the recombinant contribution improves the agreement with the latest analysis of charmonium at RHIC, which shows an absence of anomalous suppression except in the most central collisions.