Angular Dependence of the Radiative Gluon Spectrum and the Energy Loss of Hard Jets in QCD Media

TL;DR

This paper derives the angular dependence of soft gluon radiation and jet energy loss in QCD media, proposing a calorimetric measurement to analyze medium effects on jet quenching.

Contribution

It introduces a universal variable for energy loss dependence on jet cone angle and medium properties within the BDMPS formalism.

Findings

Energy loss fraction depends on the variable θ² L³ q̂

Universal behavior observed in the angular energy loss distribution

Implications for distinguishing cold and hot QCD matter

Abstract

The induced momentum spectrum of soft gluons radiated from a high energy quark propagating through a QCD medium is derived in the BDMPS formalism. A calorimetric measurement for the medium dependent energy lost by a jet with opening angle $\theta_{{\rm cone}}$ is proposed.The fraction of this energy loss with respect to the integrated one appears to be the relevant observable.It exhibits a universal behaviour in terms of the variable $\theta^2_{{\rm cone}} L^3 \hat q$ where $L$ is the size of the medium and $\hat q$ the transport coefficient. Phenomenological implications for the differences between cold and hot QCD matter are discussed.