Measurements of mass-dependent azimuthal anisotropy in central p + Au, d + Au, and 3He + Au collisions at √sNN=200 GeV
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We present measurements of the transverse-momentum dependence of elliptic flow v2 for identified pions and (anti)protons at midrapidity (|η|<0.35), in 0%–5% central p+Au and 3He+Au collisions at √sNN=200 GeV. When taken together with previously published measurements in d+Au collisions at √sNN=200 GeV, the results cover a broad range of small-collision-system multiplicities and intrinsic initial geometries. We observe a clear mass-dependent splitting of v2(pT) in d+Au and 3He+Au collisions, just as in large nucleus-nucleus (A+A) collisions, and a smaller splitting in p+Au collisions. Both hydrodynamic and transport model calculations successfully describe the data at low pT (<1.5GeV/c), but fail to describe various features at higher pT. In all systems, the v2 values follow an approximate quark-number scaling as a function of the hadron transverse kinetic energy per constituent quark (KET/nq), which was also seen previously in A+A collisions.
- Physical review C
Physical review C 97(6), 064904, 2018-06
American Physical Society