"Figure 18b-1" 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√s_NN=200 GeV的金核碰撞中，于赝快度（pseudorapidity）区间|η|<0.35内测量的单举带电强子椭圆流（inclusive charged hadron elliptic flow），其第二谐波分量记为v₂。本文同时给出了v₂在较宽横向动量（transverse momentum，p_T=0.2~8.0 GeV/c）以及碰撞中心度（centrality，0~60%）区间内的结果。为研究除集体流（collective flow）之外的关联所引发的非流效应（nonflow effects），并探究v₂的涨落特性，本文采用两种不同的分析方法开展对比研究：(1) 利用前向（|η|=3.1~3.9）和束流（|η|>6.5）赝快度区间的两套独立子探测器构建的事件平面法（event-plane method）；(2) 基于中快度区（midrapidity）探测粒子间关联提取得到的两粒子累积量法（two-particle cumulant method）。在测量的p_T区间以及0~40%中心度范围内，两种事件平面法的结果在系统误差（systematic uncertainties）范围内保持一致。在边缘（40~60%）碰撞事件中，两种事件平面法得到的v₂结果间的最大差异不超过20%。本文还对两粒子累积量法结果与标准事件平面法测量结果的对比情况进行了讨论。