University of Colorado, Boulder, Colorado 80309, USA.
Phys Rev Lett. 2010 Aug 6;105(6):062301. doi: 10.1103/PhysRevLett.105.062301. Epub 2010 Aug 4.
Differential measurements of the elliptic (v(2)) and hexadecapole (v(4)) Fourier flow coefficients are reported for charged hadrons as a function of transverse momentum (p(T)) and collision centrality or number of participant nucleons (N(part)) for Au+Au collisions at sq.rt(s(NN))=200 GeV. The v(2,4) measurements at pseudorapidity |η|≤0.35, obtained with four separate reaction-plane detectors positioned in the range 1.0<|η|<3.9, show good agreement, indicating the absence of significant Δη-dependent nonflow correlations. Sizable values for v(4)(p(T)) are observed with a ratio v(4)(p(T),N(part))/v(2)(2)(p(T),N(part))≈0.8 for 50≲N(part)≲200, which is compatible with the combined effects of a finite viscosity and initial eccentricity fluctuations. For N(part)≳200 this ratio increases up to 1.7 in the most central collisions.
椭圆（v(2)）和十六极（v(4)）傅立叶流系数的差分测量值被报告为带电强子的横向动量（p(T)）和碰撞中心度或参与核子数（N(part)）的函数，对于 Au+Au 碰撞，在 sq.rt(s(NN))=200 GeV 时。在 η|≤0.35 的赝快度范围内，使用四个分别位于 1.0<|η|<3.9 范围内的反应平面探测器获得的 v(2,4)测量值非常吻合，表明不存在显著的 Δη 依赖非流相关性。对于 50≲N(part)≲200，观察到 v(4)(p(T))的值非常大，v(4)(p(T),N(part))/v(2)(2)(p(T),N(part))≈0.8，这与有限粘度和初始各向异性波动的综合效应相兼容。对于 N(part)≳200，这个比值在最中心的碰撞中增加到 1.7。
