PHENIX results on collectivity in small systems

PHENIX has measured elliptic and triangular flow of charged hadrons in $p/d/^{3}$He$+$Au collisions at a center-of-mass energy of 200 GeV per nucleon pair, and elliptic flow in $d$+Au collisions at 200, 62.4, and 39 GeV. In order to asses the origin of collectivity in the smallest systems, these results are compared with several theoretical models that produce azimuthal particle correlations based on initial and/or final state effects. Hydrodynamical models, which include the formation of a droplet of quark-gluon plasma, provide the best simultaneous description of our observations.