Measurements of midrapidity charged particle multiplicity distributions, dN ch /dη, and midrapidity transverse-energy distributions, dET /dη, are presented for a variety of collision systems and energies. Included are distributions for Au+Au collisions at For all A+A collisions down to √ s N N = 7.7 GeV, it is observed that the midrapidity data are better described by scaling withNqp than scaling with Npart. Also presented are estimates of the Bjorken energy density, εBJ, and the ratio of dET /dη to dN ch /dη, the latter of which is seen to be constant as a function of centrality for all systems.

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identified hadrons π ± , K ± , p, andp produced at midrapidity in Cu+Au collisions at

The PHENIX experiment at the Relativistic Heavy Ion Collider has measured 2nd and 3rd order

We present the first measurements of long-range angular correlations and the transverse momentum dependence of elliptic flow v2 in high-multiplicity p+Au collisions at √ s N N = 200 GeV. A comparison of these results with previous measurements in high-multiplicity d+Au and 3 He+Au collisions demonstrates a relation between v2 and the initial collision eccentricity ε2, suggesting that the observed momentum-space azimuthal anisotropies in these small systems have a collective origin 3 and reflect the initial geometry. Good agreement is observed between the measured v2 and hydrodynamic calculations for all systems, and an argument disfavoring theoretical explanations based on initial momentum-space domain correlations is presented. The set of measurements presented here allows us to leverage the distinct intrinsic geometry of each of these systems to distinguish between different theoretical descriptions of the long-range correlations observed in small collision systems.