Medium-induced gluon branching

TL;DR

This paper advances the understanding of jet quenching by calculating medium-induced gluon branching, including transverse momentum effects and gluon correlations, showing suppression of interference effects crucial for probabilistic modeling.

Contribution

It extends the BDMPSZ theory by incorporating transverse momentum dependence and analyzing gluon correlations, providing a more complete description of soft gluon emissions in dense QCD media.

Findings

Gluons lose color coherence over a time scale comparable to the branching duration.

Interference effects between successive emissions are suppressed.

The results support a probabilistic, branching process description of soft gluon emissions.

Abstract

We study the evolution of an energetic jet which radiates gluons while propagating through a dense QCD medium modeled as a random distribution of color sources. Motivated by the heavy ion experimental program at the LHC, we focus on the medium-induced radiation of (relatively) soft gluons, which are abundantly emitted at large angles and thus can transport a small fraction of the jet energy far away from the jet axis. We perform a complete calculation of the medium-induced gluon branching in the regime where the gluons that take part in the branching undergo multiple soft scattering with the medium. We extend the BDMPSZ theory of radiative energy loss by including the transverse momentum dependence in the kernel that describes the branching and by analyzing the correlations between the two offspring gluons. We demonstrate that these gluons lose color coherence with respect to each other over a time scale that is comparable to the duration of the branching. It follows that interference effects between successive emissions are suppressed, a necessary ingredient for a description of multiple emission of soft gluons by a probabilistic, branching process.