On jet quenching parameters in strongly coupled non-conformal gauge theories

TL;DR

This paper extends the gauge/string duality approach to compute the jet quenching parameter in non-conformal gauge theories, revealing its dependence on the theory's degrees of freedom and non-universality.

Contribution

It generalizes the calculation of the jet quenching parameter to non-conformal theories, showing its non-universality and relation to the degrees of freedom.

Findings

Jet quenching parameter varies with gauge theory specifics.

Value of  increases with the number of degrees of freedom.

The parameter is not universal across different gauge theories.

Abstract

Recently Liu, Rajagopal and Wiedemann (LRW) [hep-ph/0605178] proposed a first principle, nonperturbative quantum field theoretic definition of ``jet quenching parameter'' \hat{q} used in models of medium-induced radiative parton energy loss in nucleus-nucleus collisions at RHIC. Relating \hat{q} to a short-distance behavior of a certain light-like Wilson loop, they used gauge theory-string theory correspondence to evaluate \hat{q} for the strongly coupled N=4 SU(N_c) gauge theory plasma. We generalize analysis of LRW to strongly coupled non-conformal gauge theory plasma. We find that a jet quenching parameter is gauge theory specific (not universal). Furthermore, it appears it's value increases as the number of effective adjoint degrees of freedom of a gauge theory plasma increases.