Are gluon showers inside a quark-gluon plasma strongly coupled? a theorist's test

TL;DR

This paper investigates whether gluon showers in a quark-gluon plasma can be modeled as sequential splittings or if quantum overlaps are significant, using theoretical calculations that include the LPM effect.

Contribution

It provides a leading-order calculation of quantum overlap effects in in-medium gluon showers, considering the LPM effect and their impact on jet quenching parameters.

Findings

Overlap effects can be characterized independently of the jet-quenching parameter.

Quantum overlaps may be significant, challenging the assumption of independent splittings.

The study offers a theoretical framework for understanding gluon shower dynamics in a plasma.

Abstract

We study whether in-medium showers of high-energy gluons can be treated as a sequence of individual splitting processes $g{\to}gg$, or whether there is significant quantum overlap between where one splitting ends and the next begins. Accounting for the Landau-Pomeranchuk-Migdal (LPM) effect, we calculate such overlap effects to leading order in high-energy $\alpha_{\rm s}(\mu)$ for the simplest theoretical situation. We investigate a measure of overlap effects that is independent of physics that can be absorbed into an effective value $\hat q_{\rm eff}$ of the jet-quenching parameter $\hat q$.