Measurement of two-particle correlations with respect to second- and third-order event planes in AuAu collisions at GeV

Adare, A.*; Hasegawa, Shoichi   ; Imai, Kenichi; Nagamiya, Shoji*; Sako, Hiroyuki   ; Sato, Susumu  ; Tanida, Kiyoshi   ; PHENIX Collaboration*; 451 of others*

We present measurements of azimuthal correlations of charged hadron pairs in GeV AuAu collisions after subtracting an underlying event using a model that includes higher-order azimuthal anisotropy , , and . After subtraction, the away-side ( of the highest transverse-momentum trigger ( GeV/) correlations is suppressed compared to that of correlations measured in collisions. At the lowest associated particle , the away-side shape and yield are modified. These observations are consistent with the scenario of radiative-jet energy loss. For the lowest- trigger correlations, an away-side yield exists and we explore the dependence of the shape of the away-side within the context of an underlying-event model. Correlations are also studied differentially versus event-plane angle . The angular correlations show an asymmetry when selecting the sign of the trigger-particle azimuthal angle with respect to the event plane. This asymmetry and the measured suppression of the pair yield out of plane is consistent with a path-length-dependent energy loss. No dependence can be resolved within experimental uncertainties.