Medium-induced cascade in expanding media

TL;DR

This paper investigates how different expansion scenarios of the quark-gluon plasma affect gluon emission spectra and jet suppression, revealing universal behaviors and scaling features crucial for accurate jet quenching modeling.

Contribution

It introduces a comprehensive analysis of medium expansion effects on gluon emission and jet quenching within the BDMPS-Z formalism, including novel scaling behaviors and the impact of expansion types.

Findings

Universal behavior of splitting kernels in soft gluon regime

Scaling features of gluon distribution and jet $Q_{AA}$

Differences in medium expansion can be scaled out by quenching parameters

Abstract

Detailed insight into the interplay between parton energy loss and the way deconfined medium created in heavy-ion collisions expands is of great importance for improving the understanding of the jet quenching phenomenon. In this paper we study the impact of the expansion of deconfined medium on the single-gluon emission spectrum, its resummation and the jet suppression factor ($Q_{AA}$) within the BDMPS-Z formalism. We calculate these quantities for three types of expansion scenarios, namely static, exponentially decaying and Bjorken expanding media. The distribution of medium-induced gluons is calculated using an evolution equation with splitting kernels derived from the gluon emission spectra. A universal behavior of splitting kernels is derived in the regime of soft gluon emissions when evaluated at a common effective evolution time $\tau_{eff}$. Novel scaling features of the resulting gluon distribution and jet $Q_{AA}$ are discussed. For realistic spectra valid beyond the soft-gluon emission limit, where the results are obtained by a numerical solution of the evolution equation, these features are partially replaced by a scaling expected from considering an averaged jet quenching parameter along the trajectory of propagation. Further we show that differences arising from different types of the medium expansion can be to a large extent scaled out by appropriate choice of the quenching parameter. Sizable differences among the values of the quenching parameter for different types of medium expansion point to the importance of the medium expansion for precise modeling of the jet quenching phenomenon.