Partonic effects on dijet correlations in relativistic heavy ion collisions

Abstract

Within a parton transport model, we show that diffusion wakes and Mach cone wakes produced from energy loss by a fast parton propagating in the quark-gluon plasma lead to the observed azimuthal angular correlations of hadrons in central $\mathrm{Au}+\mathrm{Au}$ collisions at RHIC. The magnitude and shape of the wakes are shown to be sensitive measures of the initial parton density and the parton scattering cross section. The shear viscosity to entropy density ratio, $\ensuremath{\eta}/s$, of the plasma is found to be remarkably similar to the lower bound $\ensuremath{\eta}/s=1/4\ensuremath{\pi}$ obtained in the AdS/CFT conjecture.