Interference between initial and final state radiation in a QCD medium

TL;DR

This paper analyzes how initial and final state radiation interfere within a QCD medium, deriving the gluon spectrum and exploring angular distributions, with implications for understanding high-energy nuclear collisions.

Contribution

It introduces a detailed derivation of the medium-induced gluon spectrum including interference effects between initial and final state radiation in a QCD medium.

Findings

Interference modifies the angular distribution of emitted gluons.

Soft gluon limit allows a probabilistic interpretation.

Results have potential phenomenological implications for nuclear collision experiments.

Abstract

We investigate the color coherence pattern between initial and final state radiation in the presence of a QCD medium. We derive the medium-induced gluon spectrum of an "asymptotic" parton which suffers a hard scattering and subsequently crosses the medium. The angular distribution of the induced gluon spectrum is modified when one includes interference terms between the incoming and the outgoing parton at finite angle between them. The coherent, incoherent and soft limits of the medium-induced gluon spectrum are studied. In the soft limit, we provide a simple and intuitive probabilistic picture which could be of interest for Monte Carlo implementations. The configuration studied here may have phenomenological consequences in high energy nuclear collisions.