A study of the correlations between jet quenching observables at RHIC
  Focusing on four types of correlation plots, $R_{\rm AA}$ vs. $v_2$, $R_{\rm AA}$ vs. $I_{\rm AA}$, $I_{\rm AA}$ vs. $v_2^{I_{\rm AA}}$ and $v_2$ vs.\ $v_2^{I_{\rm AA}}$, we demonstrate how the centrality dependence of \emph{correlations} between multiple jet quenching observables provide valuable insight into the energy loss mechanism in a quark-gluon plasma. In particular we find that a qualitative energy loss model gives a good description of $R_{\rm AA}$ vs.\ $v_2$ only when we take $\Delta E\sim l^3$ and a medium geometry generated by a model of the Color Glass Condensate. This same $\Delta E\sim l^3$ model also qualitatively describes the trigger $p_T$ dependence of $R_{\rm AA}$ vs.\ $I_{\rm AA}$ data and makes novel predictions for the centrality dependence for this $R_{\rm AA}$ vs.\ $I_{\rm AA}$ correlation. Current data suggests, albeit with extremely large uncertainty, that $v_2^{I_{\rm AA}}\gg v_2$, a correlation that is difficult to reproduce in current energy loss models. 
Jiangyong Jia, W. A. Horowitz, Jinfeng Liao
nucl-th hep-ph nucl-ex