High-pT Neutral Pion Production in Heavy Ion Collisions at SPS and RHIC

TL;DR

This paper compares high transverse momentum neutral pion production in heavy ion collisions at SPS and RHIC, revealing enhancement at SPS energies and suppression at RHIC energies, indicating different nuclear effects at these energies.

Contribution

It provides the first comparative analysis of neutral pion spectra at SPS and RHIC energies, highlighting energy-dependent nuclear modification effects.

Findings

High-pT neutral pion production is enhanced at SPS energies.

High-pT neutral pion production is suppressed at RHIC energies.

Different nuclear effects dominate at different collision energies.

Abstract

Transverse momentum spectra for neutral pions have been measured by the WA98 experiment in sqrt{s_{nn}}=17.3 GeV Pb+Pb collisions at the CERN SPS and by the PHENIX experiment in sqrt{s_{nn}}=130 GeV Au+Au collisions at RHIC. The neutral pion yields in central collisions for both reaction systems are compared to scaled transverse momentum spectra for nucleon-nucleon reactions at the respective energy. At SPS energies neutral pion production at high $p_T$ is enhanced compared to the n+n reference while at RHIC a significant suppression of high-pT neutral pions is observed.