Jet modification via $\pi^0$-hadron correlations in Au$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV

TL;DR

This paper investigates jet quenching in heavy-ion collisions by measuring neutral-pion and charged hadron correlations, revealing suppression of high-momentum fragments and enhancement of low-momentum particles, thus providing insights into energy loss mechanisms in quark-gluon plasma.

Contribution

First measurement of $I_{AA}$ and $ riangle_{AA}$ ratios as functions of azimuthal separation in Au+Au collisions at RHIC, quantifying jet modification effects.

Findings

Suppression of high-momentum jet fragments opposite the trigger.

Enhancement of low-momentum associated hadrons at wide angles.

Quantitative data on jet modification in quark-gluon plasma.

Abstract

High-momentum two-particle correlations are a useful tool for studying jet-quenching effects in the quark-gluon plasma. Angular correlations between neutral-pion triggers and charged hadrons with transverse momenta in the range 4--12~GeV/$c$ and 0.5--7~GeV/$c$, respectively, have been measured by the PHENIX experiment in 2014 for Au$+$Au collisions at $\sqrt{s_{_{NN}}}=200$~GeV. Suppression is observed in the yield of high-momentum jet fragments opposite the trigger particle, which indicates jet suppression stemming from in-medium partonic energy loss, while enhancement is observed for low-momentum particles. The ratio and differences between the yield in Au$+$Au collisions and $p$$+$$p$ collisions, $I_{AA}$ and $\Delta_{AA}$, as a function of the trigger-hadron azimuthal separation, $\Delta\phi$, are measured for the first time at the Relativistic Heavy Ion Collider. These results better quantify how the yield of low-$p_T$ associated hadrons is enhanced at wide angle, which is crucial for studying energy loss as well as medium-response effects.