"Figure 18c-3" of "Systematic Studies of Elliptic Flow Measurements in Au+Au Collisions at sqrt(s_NN) = 200 GeV"

We present inclusive charged hadron elliptic flow ($v_2$) measured over the pseudorapidity range $|\eta|$ < 0.35 in Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. Results for $v_2$ are presented over a broad range of transverse momentum ($p_{T}$ = 0.2-8.0 GeV/$c$) and centrality (0-60%). To study nonflow effects that are correlations other than collective flow, as well as the fluctuations of $v_2$, we compare two different analysis methods: (1) the event-plane method from two independent subdetectors at forward ($|\eta|$ = 3.1–3.9) and beam ($|\eta|$ > 6.5) pseudorapidities and (2) the two-particle cumulant method extracted using correlations between particles detected at midrapidity. The two event-plane results are consistent within systematic uncertainties over the measured $p_T$ and in centrality 0–40%. There is at most a 20% difference in the $v_2$ between the two event-plane methods in peripheral (40–60%) collisions. The comparisons between the two-particle cumulant results and the standard event-plane measurements are discussed.

本工作报道了在$sqrt{s_{NN}}$=200 GeV的金核（Au）碰撞中，于赝快度区间$|eta|<0.35$内测量得到的全域带电强子椭圆流（$v_2$）结果。该$v_2$结果覆盖了较宽的横向动量（$p_T$=0.2~8.0 GeV/$c$）区间与碰撞中心度（0~60%）范围。为研究除集体流之外的关联所构成的非流效应，以及$v_2$的涨落特性，本工作对比了两种不同的分析方法：(1) 利用前向（$|eta|=3.1sim3.9$）与束流端（$|eta|>6.5$）赝快度区间的两个独立子探测器获取的事件平面法；(2) 利用中快度区探测粒子间关联提取得到的两粒子累积量法。在测量覆盖的$p_T$区间与0~40%中心度范围内，两种事件平面法得到的结果在系统不确定性内保持一致。在边缘碰撞（40~60%中心度）区间内，两种事件平面法得到的$v_2$结果最大差异不超过20%。本工作还讨论了两粒子累积量法结果与标准事件平面法测量结果的对比分析。