On Drag Forces and Jet Quenching in Strongly Coupled Plasmas

TL;DR

This paper calculates the drag force on a heavy quark in strongly coupled plasmas using gauge/gravity duality, compares it with jet-quenching parameters, and explores effects of chemical potential.

Contribution

It provides a general framework for computing drag forces in arbitrary holographic backgrounds and compares these results with jet-quenching parameters in specific theories.

Findings

Drag force depends non-trivially on quark velocity.

Qualitative agreement between drag force and jet-quenching parameter in cascading gauge theory.

Jet-quenching parameter for N=4 super-Yang-Mills with chemical potential calculated.

Abstract

We compute the drag force experienced by a heavy quark that moves through plasma in a gauge theory whose dual description involves arbitrary metric and dilaton fields. As a concrete application, we consider the cascading gauge theory at temperatures high above the deconfining scale, where we obtain a drag force with a non-trivial velocity dependence. We compare our results with the jet-quenching parameter for the same theory, and find qualitative agreement between the two approaches. Conversely, we calculate the jet-quenching parameter for N=4 super-Yang-Mills with an R-charge density (or equivalently, a chemical potential), and compare our result with the corresponding drag force.