Indications of Conical Emission of Charged Hadrons at the BNL Relativistic Heavy Ion Collider

Abstract

Three-particle azimuthal correlation measurements with a high transverse momentum trigger particle are reported for $pp$, $d+\mathrm{Au}$, and $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{{s}_{\mathrm{NN}}}=200\text{ }\text{ }\mathrm{GeV}$ by the STAR experiment. Dijet structures are observed in $pp$, $d+\mathrm{Au}$ and peripheral $\mathrm{Au}+\mathrm{Au}$ collisions. An additional structure is observed in central $\mathrm{Au}+\mathrm{Au}$ data, signaling conical emission of correlated charged hadrons. The conical emission angle is found to be $\ensuremath{\theta}=1.37\ifmmode\pm\else\textpm\fi{}0.02(\mathrm{stat}{)}_{\ensuremath{-}0.07}^{+0.06}(\mathrm{syst})$, independent of ${p}_{\ensuremath{\perp}}$.