Direct Photon-Hadron Correlations Measured with PHENIX

Abstract Direct photon- hadroncorrelations greatly improve our ability to perform jet tomography in heavy-ion collisions because the momentum of the direct photon can be used to constrain the initial momentum of the opposing jet. By comparing the spectrum of away-side hadronsobserved in heavy ion collisions to the spectrum seen in nucleon collisions we can quantify the medium modification to the fragmentation functiondue to energy loss of the away-side parton. High p T direct photon- hadroncorrelations have been measured with the PHENIX detectorusing a statistical subtraction method to remove the photon contribution from meson decays. The increased integrated luminosity in the most recent Au+Au RHIC run at s N N = 200 GeV provides substantially improved statistical precision and enhances the kinematic reach. These measurements are compared to PHENIX p+p results and several theoretical models of energy loss. In addition, we compare direct photon- hadronand π 0 - hadroncorrelations.