Gluon radiation inside a flowing medium

TL;DR

This paper analyzes how gluon emission spectra from high-energy quarks are affected by flowing QCD media, revealing significant flow-induced modifications to the gluon distribution and azimuthal patterns.

Contribution

It provides the first detailed calculation of flow effects on gluon radiation spectra, including substantial corrections due to transverse flow in a QCD medium.

Findings

Flow significantly alters gluon spectra and angular distributions.

Transverse flow causes gluon emission to align with flow direction.

Corrections are substantial even at moderate energies and flow velocities.

Abstract

We compute the spectrum of gluons emitted by a highly energetic quark inside a flowing QCD medium, focusing on the soft gluon limit at first order in the opacity expansion. Specifically, we derive the leading energy-suppressed corrections to the double differential final parton distribution, and show that they are substantial for both static and flowing matter. In particular, we demonstrate that the corrections due to the transverse flow become large even at moderate energies and flow velocities, affecting drastically both the shape and magnitude of the spectrum. We observe that the final transverse momentum of the emitted gluon tends to align along the flow direction, resulting in a non-trivial azimuthal distribution. These results can be directly implemented into the estimation of multiple observables to get a better understanding of the jet-medium interaction processes in HICs.