System size and energy dependence of jet-induced hadron pair correlation shapes in Cu+Cu and Au+Au collisions at sNN=200 and 62.4 GeV

We present azimuthalangle correlations of intermediate transverse momentum (1-4 GeV/c) hadrons from dijets in Cu+Cu and Au+Au collisionsat root s(NN)=62.4 and 200 GeV. The away-side dijet induced azimuthalcorrelation is broadened, non-Gaussian, and peaked away from Delta phi=pi in central and semicentral collisionsin all the systems. The broadening and peak location are found to depend upon the number of participants in the collision, but not on the collisionenergy or beam nuclei. These results are consistent with sound or shock wave models, but pose challenges to Cherenkov gluon radiation models.