Jet quenching parameter in QCD kinetic theory

Abstract

We study the jet quenching parameter q^ in a nonequilibrium plasma using the QCD effective kinetic theory. We discuss subleading terms at large jet momentum p, show that our expression for q^ reproduces thermal results at small and large transverse momentum cutoffs for infinite p, and construct an interpolation between these limits to be used in phenomenological applications. Using simple nonequilibrium distributions that model pertinent features of the bottom-up thermalization scenario, we analytically assess how anisotropy, underoccupation, or overoccupation affect the jet quenching parameter. Our work provides more details on the q^ formula used in our preceding work [ ] and sets the stage for further numerical studies of jet momentum broadening in the initial stages of heavy-ion collisions from QCD kinetic theory. Published by the American Physical Society 2024