Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA.
Phys Rev Lett. 2010 Apr 9;104(14):142301. doi: 10.1103/PhysRevLett.104.142301. Epub 2010 Apr 8.
This Letter presents the first measurement of event-by-event fluctuations of the elliptic flow parameter v(2) in Au+Au collisions at square root(s(NN))=200 GeV as a function of collision centrality. The relative nonstatistical fluctuations of the v(2) parameter are found to be approximately 40%. The results, including contributions from event-by-event elliptic flow fluctuations and from azimuthal correlations that are unrelated to the reaction plane (nonflow correlations), establish an upper limit on the magnitude of underlying elliptic flow fluctuations. This limit is consistent with predictions based on spatial fluctuations of the participating nucleons in the initial nuclear overlap region. These results provide important constraints on models of the initial state and hydrodynamic evolution of relativistic heavy ion collisions.
这封信提出了在 sqrt(s(NN))=200 GeV 的 Au+Au 碰撞中，作为碰撞中心度函数的椭圆流参数 v(2) 的逐事件涨落的第一次测量。发现 v(2) 参数的相对非统计涨落约为 40%。这些结果包括逐事件椭圆流涨落的贡献，以及与反应平面（非流关联）无关的方位角关联的贡献，为基础椭圆流涨落的幅度设定了上限。这一限制与基于初始核重叠区域中参与核子的空间涨落的预测是一致的。这些结果为相对论重离子碰撞的初始状态和流体力学演化模型提供了重要的约束。
