Speaker
Description
The first evidence of jet quenching was observed at RHIC via suppression of single high $p_T$ hadron
$R_{AA}$ and the disappearance of the awayside jet peak in two-particle correlations. Hadron
$R_{AA}$ and two particle correlations continue to be useful probes of the QGP in heavy ion collisions,
since the particles involved are fragments of the jets produced in the initial hard scattering. PHENIX recently improved the width measurements extracted from $\pi^{0}$-hadron correlations after removing the higher ordered flow terms in the underlying event. Measurements of the awayside jet correlated with direct photons have shown an increase in low momentum particle production at wide angles consistent with theoretical expectations for energy loss. The use of isolation cuts to select direct photons now allows us to measure this effect as a function of centrality. The system size dependence of energy loss is further investigated at PHENIX by measuring the absolute yield and $R_{AA}$ for various hadron species at high $p_T$ in several collision systems including U+U and Cu+Au. This talk will present the newest PHENIX $R_{AA}$ and two particle correlation measurements and their role in our understanding of jet quenching and medium response in heavy ion collisions.
