Minijet thermalization and jet transport coefficients in QCD kinetic theory

TL;DR

This paper uses QCD kinetic theory to study how high-momentum partons, or minijets, thermalize in a Quark-Gluon Plasma, revealing the importance of medium recoil effects on jet transport coefficients and thermalization times.

Contribution

It introduces a kinetic simulation framework that incorporates medium recoil effects, improving the accuracy of jet quenching parameter estimates in QGP.

Findings

Recoil effects are essential for accurate jet transport coefficient calculations.

Minijet thermalization time correlates well with the jet quenching parameter $_q$.

The study provides a phenomenological estimate of minijet quenching time in heavy-ion collisions.

Abstract

We apply weakly coupled QCD kinetic theory to investigate the thermalization of high-momentum on-shell partons (minijets) in a Quark-Gluon Plasma (QGP). Our approach incorporates isotropic hard thermal loop screening to model soft quark and gluon exchanges, allowing us to verify consistency with established analytic results of jet transport coefficients. We perform kinetic simulations of minijets propagating through a thermal gluon plasma, incorporating both collinear radiation and elastic scatterings. The resulting evolution is compared to predictions from jet transport coefficients, including the longitudinal and transverse jet-quenching parameters $\hat{q}$, energy loss, and the drag coefficient. We find that standard definitions of jet transport coefficients neglect the contributions from recoiling medium particles. Including these contributions restores consistency with the kinetic evolution. Finally, we show that the minijet thermalization time scales remarkably well with $\hat{q}$ and we produce a phenomenological estimate of the minijet quenching time in heavy-ion collisions.