Small-$x$ evolution of jet quenching parameter

TL;DR

This paper derives an evolution equation for the jet quenching parameter at small x, showing it evolves with x at a rate slightly less than the gluon distribution function, enhancing understanding of parton-medium interactions.

Contribution

It introduces a high energy evolution equation for the jet quenching parameter based on transverse deflection probability, extending previous concepts to small-x regimes.

Findings

Jet quenching parameter ${ ilde q}(x)$ evolves with x at an exponent of approximately 0.9 times the strong coupling.

The evolution rate of ${ ilde q}(x)$ is slightly less than that of the gluon distribution function ${ ilde G}(x)$.

Provides a theoretical framework for understanding jet quenching in high-energy QCD processes.

Abstract

Concept of transverse deflection probability of a parton that travels through strongly interacting medium, recently introduced by D'Eramo, Liu and Rajagopal, have been used to derive high energy evolution equation for the jet quenching parameter in stochastic multiple scatterings regime. Jet quenching parameter, ${\hat q}(x)$, appears to evolve with $x$, with an exponent $0.9{\bar \alpha}_s$, which is slightly less than that of $x {\cal G} (x)$ where ${\cal G} (x)$ is the gluon distribution function.