Azimuthal Anisotropy and Correlations in the Hard Scattering Regime at RHIC

Azimuthal anisotropy ($v_2$) and two-particle angular correlations of high $p_T$ charged hadrons have been measured in $\mathrm{A}\mathrm{u}+\mathrm{A}\mathrm{u}$ collisions at $\sqrt{s_{NN}}=130\mathrm{G}\mathrm{e}\mathrm{V}$ for transverse momenta up to $6\mathrm{G}\mathrm{e}\mathrm{V}/c$, where hard processes are expected to contribute significantly. The two-particle angular correlations exhibit elliptic flow and a structure suggestive of fragmentation of high $p_T$ partons. The monotonic rise of $v_2(p_T)$ for $p_T<2\mathrm{G}\mathrm{e}\mathrm{V}/c$ is consistent with collective hydrodynamical flow calculations. At $p_T>3\mathrm{G}\mathrm{e}\mathrm{V}/c$, a saturation of $v_2$ is observed which persists up to $p_T=6\mathrm{G}\mathrm{e}\mathrm{V}/c$.