Direct photon-hadron correlations measured with the PHENIX detector

Abstract Photontagged jets are an excellent probe of the hot dense matter created in heavy ion collisions at RHIC. Since photonsinteract weakly and are not modified by the strongly coupled medium, the measured photonmomentum approximately balances that of the away-side parton. Therefore, the modification of the fragmentation functioncan be obtained by comparing the spectra of the away-side yields in direct photon- hadroncorrelations in Au+Au collisions to those in p+p. Direct photon- hadroncorrelations are measured with the PHENIX detectorin p+p and Au+Au collisions at s N N = 200 GeV at RHIC. We employ a statistical subtraction method to remove the contribution of decay photonsfrom the inclusive photon- hadroncorrelations. For the p+p analysis, we developed event by event techniques to improve the systematic uncertainty in the baseline measurement. Compared to previous measurements, this Au+Au result extends to higher ξ (lower z T ) where a medium-induced modification of jet fragmentation is observed.