Systematic study of high-$p_T$ hadron and photon production with the PHENIX experiment

TL;DR

This paper presents a comprehensive study of high-$p_T$ hadron and photon production in various collision systems and energies at RHIC, highlighting suppression patterns and baseline measurements for understanding quark-gluon plasma effects.

Contribution

It provides the first detailed energy and system-size dependence analysis of high-$p_T$ suppression and includes new direct photon measurements at RHIC energies.

Findings

Suppression of high-$p_T$ hadrons varies with system size and energy.

Direct photons serve as an unaffected baseline for hard processes.

Energy dependence of suppression patterns is characterized.

Abstract

The suppression of hadrons with large transverse momentum ($p_{\rm T}$) in central Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200 GeV compared to a binary scaled p+p reference is one of the major discoveries at RHIC. To understand the nature of this suppression PHENIX has performed detailed studies of the energy and system-size dependence of the suppression pattern, including the first RHIC measurement near SPS energies. An additional source of information is provided by direct photons. Since they escape the medium basically unaffected they can provide a high $p_{\rm T}$ baseline for hard-scattering processes. An overview of hadron production at high $p_{\rm T}$ in different colliding systems and at energies from $\sqrt{s_{\rm NN}} = 22.4 - 200$ GeV will be given. In addition, the latest direct photon measurements by the PHENIX experiment shall be discussed.