Jet-Hadron Correlations in sqrt{s_{NN}} = 200 GeV p+p and Central Au+Au Collisions

TL;DR

This study investigates jet-hadron correlations in proton-proton and gold-gold collisions at 200 GeV, revealing medium effects such as suppression and enhancement of associated hadrons due to parton energy loss.

Contribution

It provides new measurements of azimuthal correlations in heavy-ion collisions, highlighting medium modifications of jet structures at RHIC energies.

Findings

Suppressed high-$p_T$ associated hadron yield in Au+Au collisions

Enhanced low-$p_T$ associated hadron yield in Au+Au collisions

Evidence of medium-induced parton energy loss

Abstract

Azimuthal angular correlations of charged hadrons with respect to the axis of a reconstructed (trigger) jet in Au+Au and p+p collisions at $\sqrt{s_{\text{NN}}} = 200 \text{GeV}$ in STAR are presented. The trigger jet population in Au+Au collisions is biased towards jets that have not interacted with the medium, allowing easier matching of jet energies between Au+Au and p+p collisions while enhancing medium effects on the recoil jet. The associated hadron yield of the recoil jet is significantly suppressed at high transverse momentum ($p_{\text{T}}^{\text{assoc}}$) and enhanced at low $p_{\text{T}}^{\text{assoc}}$ in 0-20% central Au+Au collisions compared to p+p collisions, which is indicative of medium-induced parton energy loss in ultrarelativistic heavy-ion collisions.