Thermalization of mini-jets in a quark-gluon plasma

TL;DR

This paper investigates how high-energy jets in a quark-gluon plasma thermalize, showing that soft gluons from jet branching rapidly reach thermal equilibrium with the medium, influencing jet evolution.

Contribution

It provides a comprehensive analytical and numerical analysis of soft component thermalization in jet propagation through QGP, highlighting the rapid equilibration process.

Findings

Soft gluons thermalize faster than the jet lifetime

Thermalized gluons form a hydrodynamic tail behind the jet

Mini-jet evolution involves multiple branching and rapid thermalization

Abstract

We present the complete physical picture for the evolution of a high-energy jet propagating through a weakly-coupled quark-gluon plasma (QGP) by analytical and numerical investigation of thermalization of the soft components of the jet. Our results support the following physical picture: the leading particle emits a significant number of mini-jets which promptly evolve via multiple branching and thus degrade into a myriad of soft gluons, with energies of the order of the medium temperature $T$. Via elastic collisions with the medium constituents, these soft gluons relax to local thermal equilibrium with the plasma over a time scale which is considerably shorter than the typical lifetime of the mini-jet. The thermalized gluons form a tail which lags behind the hard components of the jet. Together with the background QGP, they behave hydrodynamically.