Probing Transverse Momentum Broadening in Heavy Ion Collisions

TL;DR

This paper investigates how high-energy jets lose transverse momentum in quark-gluon plasma during heavy ion collisions, highlighting the dominance of different effects at LHC and RHIC energies and proposing future experimental studies.

Contribution

It combines soft gluon radiation and medium effects to explain dijet azimuthal de-correlation, clarifying the energy-dependent roles of Sudakov and medium broadening effects.

Findings

Sudakov effects dominate at LHC energies.

Medium effects are significant at RHIC energies.

Future RHIC experiments can reveal jet energy loss mechanisms.

Abstract

We study the dijet azimuthal de-correlation in relativistic heavy ion collisions as an important probe of the transverse momentum broadening effects of a high energy jet traversing the quark-gluon plasma. We take into account both the soft gluon radiation in vacuum associated with the Sudakov logarithms and the jet P_T-broadening effects in the QCD medium. We find that the Sudakov effects are dominant at the LHC, while the medium effects can play an important role at RHIC energies. This explains why the LHC experiments have not yet observed sizable P_T-broadening effects in the measurement of dijet azimuthal correlations in heavy ion collisions. Future investigations at RHIC will provide a unique opportunity to study the P_T-broadening effects and help to pin down the underlying mechanism for jet energy loss in a hot and dense medium.