Testing AdS/CFT Drag and pQCD Heavy Quark Energy Loss

TL;DR

This paper compares perturbative QCD and AdS/CFT models for heavy quark energy loss in nuclear collisions, highlighting the ratio of charm to bottom suppression as a key observable for distinguishing theories.

Contribution

It introduces the ratio of charm to bottom nuclear modification factors as a robust experimental observable to differentiate between theoretical models of heavy quark energy loss.

Findings

The ratio $R_{AA}^c/R_{AA}^b$ is insensitive to extreme model extrapolations.

Both models can fit individual $R_{AA}$ data at LHC.

The ratio provides a clear signature to test theoretical frameworks.

Abstract

We present charm and bottom nuclear modification factors for RHIC and LHC using Standard Model perturbative QCD and recent AdS/CFT string drag energy loss models. We find that extreme extrapolations to LHC mask potential experimentally determinable differences in the individual $R_{AA}$s but that their ratio, $R_{AA}^c/R_{AA}^b$ as a function of transverse momentum is a remarkably robust observable for finding deviations from either theoretical framework.