Non-equilibrium charmonium regeneration in strongly coupled quark-gluon plasma

The evaluation of quarkonium regeneration in ultrarelativistic heavy-ion collisions (URHICs) requires the knowledge of the heavy-quark phase space distributions in the expanding quark-gluon plasma (QGP) fireball. We employ a semi-classical charmonium transport approach where regeneration processes explicitly account for the time-dependent spectra of charm quarks via Langevin simulations of their diffusion. The inelastic charmonium rates and charm-quark transport coefficients are computed from the same charm-medium interaction. The latter is modeled by perturbative rates, augmented with a K-factor to represent nonperturbative interaction strength and interference effect. Using central 5.02 TeV Pb-Pb collisions as a test case we find that a good description of the measured J/psi yield and its transverse -momentum dependence can be achieved if a large K >= 5 is employed while smaller values lead to marked discrepancies. This is in line with open-charm phenomenology in URHICs, where nonperturbative interactions of similar strength are required. Our approach establishes a common transport framework for a microscopic description of open and hidden heavy-flavor (HF) observables that incorporates both nonperturbative and non-equilibrium effects, and thus enhances the mutual constraints from experiment on the extraction of transport properties of the QGP. (C) 2022 The Author(s). Published by Elsevier B.V.

Automated summary

This paper investigates the quarkonium regeneration in ultrarelativistic heavy-ion collisions and proposes a semi-classical charmonium transport approach. The study finds that a good description of the measured J/psi yield and its transverse-momentum dependence can be achieved if a large K >= 5 is employed.