Direct Observation of Dijets in CentralAu+AuCollisions atsNN=200 GeV

Abstract

The STAR Collaboration at the Relativistic Heavy Ion Collider reports measurements of azimuthal correlations of high transverse momentum ($p_T$) charged hadrons in $\mathrm{Au}+\mathrm{Au}$ collisions at higher $p_T$ than reported previously. As $p_T$ is increased, a narrow, back-to-back peak emerges above the decreasing background, providing a clear dijet signal for all collision centralities studied. Using these correlations, we perform a systematic study of dijet production and suppression in nuclear collisions, providing new constraints on the mechanisms underlying partonic energy loss in dense matter.