Thermalization and isotropization of heavy quarks in a non-Markovian medium in high-energy nuclear collisions
Pooja, Santosh K. Das, Vincenzo Greco, Marco Ruggieri
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 nonstationary medium with a noise whose time correlator decays as a power law (heavy-tailed noise). We assume the correlations decay with an exponent $\ensuremath{\beta}\ensuremath{-}1$, $0\ensuremath{\le}\ensuremath{\beta}<1$; we treat $\ensuremath{\beta}$ 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 timescale 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.