Thermalization and isotropization of heavy quarks in a non-Markovian medium in high-energy nuclear collisions

TL;DR

This paper investigates how non-Markovian, power-law correlated noise influences the thermalization and isotropization of heavy quarks in a high-energy nuclear collision medium, revealing that memory effects slow dynamics and affect charm more than beauty quarks.

Contribution

It introduces a generalized Langevin framework with power-law correlated noise to study non-Markovian effects on heavy quark thermalization in nuclear collisions.

Findings

Memory effects slow down heavy quark dynamics.

Thermalization and isotropization occur on similar timescales with realistic initial conditions.

Charm quarks are more affected by memory than beauty quarks.

Abstract

We study the isotropization and thermalization of heavy quarks in a non-Markovian medium in high energy nuclear collisions. In particular, we analyze the case of a non-stationary medium with a noise whose time-correlator decays as a power law (heavy tailed noise). We assume the correlations decay with an exponent $\beta-1$, $0\leq\beta<1$; we treat $\beta$ as a free parameter. We analyze the effect of memory on the thermalization and isotropization of heavy quarks in the medium via a generalized Langevin equation. In general, we find that memory slows down the dynamics of heavy quarks; moreover, thermalization and isotropization happen on the same time scale once a realistic initialization is considered. We also find that while the effect on charm quarks can be relevant, beauty quarks are hardly affected by memory in the quark-gluon plasma phase. Finally, we comment on the effect of memory on the estimate of $D_s$ of charm and beauty.