Heavy Quark Momentum Broadening in a Non-Abelian Plasma away from Thermal Equilibrium

TL;DR

This study uses classical-statistical lattice simulations to analyze how heavy quarks gain momentum in a non-equilibrium non-Abelian plasma, revealing non-perturbative effects and differences from equilibrium expectations.

Contribution

It introduces a new method to extract momentum broadening for relativistic quarks in non-equilibrium gauge fields and provides quantitative results for charm and bottom quarks.

Findings

Quarks exhibit non-perturbative momentum distribution features over time.

The momentum diffusion coefficient differs significantly from the heavy quark limit.

Quarks transition from correlated kicks to a diffusive regime.

Abstract

We perform classical-statistical real-time lattice simulations to compute real-time spectral functions and momentum broadening of quarks in the presence of strongly populated non-Abelian gauge fields. Based on a novel methodology to extract the momentum broadening for relativistic quarks, we find that the momentum distribution of quarks exhibit interesting non-perturbative features as a function of time due to correlated momentum kicks it receives from the medium, eventually going over to a diffusive regime. We extract the momentum diffusion coefficient for a mass range describing charm and bottom quarks and find sizeable discrepancies from the heavy quark limit.