PHENIX Measurement of High-$p_T$ Hadron-hadron and Photon-hadron Azimuthal Correlations

TL;DR

This paper reports measurements of high-$p_T$ hadron-hadron and photon-hadron azimuthal correlations in different collision systems, providing insights into medium effects on jets and photon-associated hadron suppression.

Contribution

It presents the first measurement of direct photon-hadron correlations in $ ext{Au}$ and $ ext{pp}$ collisions, comparing jet modifications across systems.

Findings

Near-side yields are consistent with zero in both systems.

Jet yields on the away side suggest suppression of photon-associated hadrons in $ ext{Au}$ collisions.

Comparison of jet widths and yields reveals medium effects on jets.

Abstract

High-$p_T$ hadron-hadron correlations have been measured with the PHENIX experiment in $\Cu$ and $\pp$ collisions at $\sqrt{s_{NN}}=200$ GeV. A comparison of the jet widths and yields between the two colliding systems allows us to study the medium effect on jets. We also present a first measurement of direct photon-hadron correlations in $\Au$ and $\pp$ collisions. We find that the near-side yields are consistent with zero in both systems. By comparing the jet yields on the away side, we observe a suggestion of the expected suppression of hadrons associated with photons in $\Au$ collisions.