Event-by-event azimuthal anisotropy of jet quenching in relativistic heavy ion collisions

TL;DR

This study systematically quantifies how jet quenching anisotropy responds to initial geometry fluctuations in heavy ion collisions, providing insights into jet-medium interactions at RHIC and LHC energies.

Contribution

It introduces a detailed event-by-event analysis of jet quenching azimuthal anisotropy and constrains models of jet energy loss based on harmonic responses to initial fluctuations.

Findings

Jet response harmonics are sensitive to quenching models and initial conditions.

Constraints on path-length and medium-density dependence of jet energy loss.

Hard-soft di-hadron correlations can explain the observed 'hard-ridge' phenomenon.

Abstract

In this paper we present with full details a systematic quantification, on an even-by-event basis, of the hard probe response to the geometry and fluctuations of the hot QCD matter created in heavy ion collisions at both the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). The azimuthal anisotropy of jet quenching is extracted and decomposed as harmonic responses (for n=1,2,3,4,5,6) to the corresponding harmonics in the fluctuating initial condition. We show that such jet response harmonics are sensitive to the jet quenching models as well as to the bulk matter initial compositions. By studying these for all centralities at both RHIC and LHC energies we put a strong constraint on the path-length and medium-density dependence of jet energy loss. We also examine the hard-soft di-hadron correlation arising from the hard and soft sectors' responses to the common initial fluctuations. We demonstrate that the experimentally observed "hard-ridge" can be explained this way and that its dependence on the trigger-azimuthal-angle could also be qualitatively understood.