Jet thermalization in QCD kinetic theory

TL;DR

This study uses QCD kinetic theory to analyze how high-energy jets lose energy and thermalize in a Quark-Gluon Plasma, highlighting the role of turbulent gluon cascades and jet cone size in jet quenching.

Contribution

It provides a detailed numerical analysis of jet energy loss mechanisms and the impact of jet cone size on medium response in QGP.

Findings

Energy loss occurs mainly via radiative turbulent gluon cascade.

Angular structure of cascade is initially collimated, then broadens at thermalization.

Jet cone size influences sensitivity to medium response.

Abstract

We perform numerical studies in QCD kinetic theory to investigate the energy and angular profiles of a high energy parton - as a proxy for a jet produced heavy ion collisions - passing through a Quark-Gluon Plasma (QGP). We find that the fast parton loses energy to the plasma mainly via a radiative turbulent gluon cascade that transport energy locally from the jet down to the temperature scale where dissipation takes place. In this first stage, the angular structure of the turbulent cascade is found to be relatively collimated. However, when the lost energy reaches the plasma temperature is it rapidly transported to large angles w.r.t. the jet axis and thermalizes. We investigate the contribution of the soft jet constituents to the total jet energy. We show that for jet opening angles of about 0.3 rad or smaller the effect is negligible. Conversely, larger opening angles become more and more sensitive to the thermal component of the jet and thus to medium response. Our result showcase the importance of the jet cone size in mitigating or enhancing the details of dissipation in jet quenching observables.