Measurements of mass-dependent azimuthal anisotropy in central + Au, + Au, and He + Au collisions at = 200 GeV
=200GeVでの + Au, + Au, and He + Au中心衝突における質量依存方位角異方性の測定
Adare, A.*; 長谷川 勝一 ; 今井 憲一; 佐甲 博之 ; 佐藤 進 ; 谷田 聖 ; PHENIX Collaboration*; 他347名*
Adare, A.*; Hasegawa, Shoichi; Imai, Kenichi; Sako, Hiroyuki; Sato, Susumu; Tanida, Kiyoshi; PHENIX Collaboration*; 347 of others*
We present measurements of the transverse-momentum dependence of elliptic flow for identified pions and (anti)protons at midrapidity (), in 0% - 5% central + Au and He + Au collisions at = 200 GeV. When taken together with previously published measurements in + Au collisions at = 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 in + Au and He + Au collisions, just as in large nucleus-nucleus ( + ) collisions, and a smaller splitting in + Au collisions. Both hydrodynamic and transport model calculations successfully describe the data at low ( GeV/), but fail to describe various features at higher . In all systems, the values follow an approximate quark-number scaling as a function of the hadron transverse kinetic energy per constituent quark(), which was also seen previously in + collisions.