Strong-coupling Jet Energy Loss from AdS/CFT

TL;DR

This paper introduces a new holographic model for light hadron jets at strong coupling, enabling the first self-consistent calculation of jet suppression that aligns well with LHC data, and highlights the sensitivity of thermalization distance to initial conditions.

Contribution

It presents a novel holographic jet definition and a strong-coupling calculation of jet quenching, revealing the importance of initial conditions and a new energy loss behavior.

Findings

Jet nuclear modification factor $R_{AA}$ matches LHC data.

Thermalization distance is highly sensitive to initial conditions.

Energy loss rate shows a late-time Bragg peak.

Abstract

We propose a novel definition of a holographic light hadron jet and consider the phenomenological consequences, including the very first fully self-consistent, completely strong-coupling calculation of the jet nuclear modification factor $R_{AA}$, which we find compares surprisingly well with recent preliminary data from LHC. We show that the thermalization distance for light parton jets is an extremely sensitive function of the \emph{a priori} unspecified string initial conditions and that worldsheets corresponding to non-asymptotic energy jets are not well approximated by a collection of null geodesics. Our new string jet prescription, which is defined by a separation of scales from plasma to jet, leads to the re-emergence of the late-time Bragg peak in the instantaneous jet energy loss rate; unlike heavy quarks, the energy loss rate is unusually sensitive to the very definition of the string theory object itself. A straightforward application of the new jet definition leads to significant jet quenching, even in the absence of plasma. By renormalizing the in-medium suppression by that in the vacuum we find qualitative agreement with preliminary CMS $R_{AA}^{jet}(p_T)$ data in our simple plasma brick model. We close with comments on our results and an outlook on future work.