Antiangular Ordering of Gluon Radiation in QCD Media

TL;DR

This paper reveals a novel antiangular ordering mechanism in medium-induced gluon radiation within QCD media, highlighting how color coherence affects jet evolution in quark-gluon plasma.

Contribution

It introduces the concept of antiangular ordering due to in-medium color coherence, a new effect not accounted for in previous models of jet quenching.

Findings

Medium-induced gluon spectrum retains vacuum-like properties.

Collinear singularity is regulated by pair opening angle.

Angular separation between vacuum and medium radiation is established.

Abstract

We investigate angular and energy distributions of medium-induced gluon emission off a quark-antiquark antenna in the framework of perturbative QCD as an attempt toward understanding, from first principles, jet evolution inside the quark-gluon plasma. In-medium color coherence between emitters, neglected in all previous calculations, leads to a novel mechanism of soft-gluon radiation. The structure of the corresponding spectrum, in contrast with known medium-induced radiation, retains some properties of the vacuum case; in particular, it exhibits a soft divergency. However, as opposed to the vacuum, the collinear singularity is regulated by the pair opening angle, leading to a strict angular separation between vacuum and medium-induced radiation, denoted as antiangular ordering. We comment on the possible consequences of this new contribution for jet observables in heavy-ion collisions.