Elliptic and hexadecapole flow of charged hadrons in Au+Au collisions at sqrt(s_NN) = 200 GeV

TL;DR

This paper reports detailed measurements of elliptic and hexadecapole flow coefficients for charged hadrons in Au+Au collisions at 200 GeV, revealing insights into the medium's viscosity and initial state fluctuations.

Contribution

It provides the first comprehensive differential measurements of v_2 and v_4 across various centralities and pseudorapidities, confirming the consistency of flow signals and their relation to theoretical models.

Findings

v_4(p_T) is sizable with a ratio v_4/v_2^2~0.8 for 50<N_part<200

The v_4/v_2^2 ratio increases to 1.7 in the most central collisions

Flow measurements are consistent across different pseudorapidity ranges

Abstract

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 the number of participant nucleons (N_part) for Au+Au collisions at sqrt(s_NN)=200 GeV. The v_{2,4} measurements at pseudorapidity |\eta|<=0.35 obtained with four separate reaction plane detectors positioned in the range 1.0<|\eta|<3.9 show good agreement, indicating the absence of significant \eta-dependent nonflow perturbations. 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.