PHENIX results on elliptic and triangular flow with geometry-engineered small systems at 200 GeV

To investigate the role of the initial spatial distribution of the collision system in driving final-state particle distributions, RHIC operated with three different collision species, p/d/³He+Au, which have intrinsic circularity, ellipticity, and triangularity, respectively, at 200 GeV center-of-mass energy. We present the 5% most central events in each system which were analyzed using the event plane method to determine the flow coefficients, v_n, for the second and third harmonics. To investigate the role of the local particle density, we also study the flow correlations comparing these systems for events with the same average number of participants.

Comparisons are made to hydrodynamical, parton transport, and initial-state momentum correlation models, each of which produce azimuthal anisotropies in the final-state particle distributions through different mechanisms.  Hydrodynamical models offer the best simultaneous description 
of all presented observables.