Probing Transverse Momentum Broadening via Dihadron and Hadron-jet Angular Correlations in Relativistic Heavy-ion Collisions

TL;DR

This paper develops a systematic theoretical framework to analyze angular correlations in high-energy collisions, enabling extraction of medium-induced transverse momentum broadening and jet quenching parameters from experimental data.

Contribution

It introduces a resummation formalism for the first time to describe dihadron and hadron-jet correlations in heavy-ion collisions, establishing a baseline and extracting key medium parameters.

Findings

Medium-induced broadening $raket{p_ot^2}$ estimated at 13 GeV$^2$ for quark jets at RHIC.

Resummation formalism successfully describes angular correlation data in $pp$ and peripheral $AA$ collisions.

Extraction of jet quenching parameter $raket{ ilde{q}}$ from angular decorrelations.

Abstract

Dijet, dihadron, hadron-jet angular correlations have been reckoned as important probes of the transverse momentum broadening effects in relativistic nuclear collisions. When a pair of high-energy jets created in hard collisions traverse the quark-gluon plasma produced in heavy-ion collisions, they become de-correlated due to the vacuum soft gluon radiation associated with the Sudakov logarithms and the medium-induced transverse momentum broadening. For the first time, we employ the systematical resummation formalism and establish a baseline calculation to describe the dihadron and hadron-jet angular correlation data in $pp$ and peripheral $AA$ collisions where the medium effect is negligible. We demonstrate that the medium-induced broadening $\langle p_\perp^2\rangle$ and the so-called jet quenching parameter $\hat q$ can be extracted from the angular de-correlations observed in $AA$ collisions. A global $\chi^2$ analysis of dihadron and hadron-jet angular correlation data renders the best fit $\langle p_\perp^2 \rangle \sim 13~\textrm{GeV}^2$ for a quark jet at RHIC top energy. Further experimental and theoretical efforts along the direction of this work shall significantly advance the quantitative understanding of transverse momentum broadening and help us acquire unprecedented knowledge of jet quenching parameter in relativistic heavy-ion collisions.