On jet quenching parameters in strongly coupled non-conformal 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.