Differential probes of medium-induced energy loss
Revised: 30 May 2005
Published online: 5 August 2005
Results from the PHENIX experiment of measurements of high- particle production presented at the Hard Probes 2004 Conference are summarized. This paper focuses on a sub-set of the measurements presented at the conference, namely the suppression of production at moderate to high as a function of angle with respect to the collision reaction plane, , for different collision centralities. The data are presented in the form of nuclear modification factor as a function of angle with respect to the reaction plane, . The data are analyzed using empirical estimates of the medium-induced energy loss obtained from the values. A geometric analysis is performed with the goal of understanding the simultaneous dependence of R AA on and centrality. We find that the centrality and dependence of the suppression can be made approximately consistent using an admittedly over-simplistic description of the geometry of the jet propagation in the medium but only if the energy loss is effectively reduced for short parton path lengths in the medium. We find that with a more "canonical" treatment of the quenching geometry, the suppression varies more rapidly with than would be expected from the centrality dependence of the suppression.
© Springer-Verlag, 2005