Elliptic and Hexadecapole Flow of Charged Hadrons in Au + Au Collisions at s_(NN)~(1/2)=200GeV

摘要

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 s_(NN)~(1/2)= 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 A 77-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_(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.