Measurements of Higher-Order Flow Harmonics in Au+Au Collisions at sqrt(s_NN) = 200 GeV

TL;DR

This paper measures higher-order flow harmonics in gold-gold collisions at 200 GeV, providing insights into the initial collision geometry and the medium's viscosity through comparison with hydrodynamic models.

Contribution

It presents detailed measurements of flow coefficients v_n for n=2,3,4, and compares them with hydrodynamic models to constrain the viscosity of the quark-gluon plasma.

Findings

Flow coefficients v_n are well described by hydrodynamic models.

Results constrain the viscosity to entropy density ratio eta/s.

Correlation among event planes enhances understanding of initial conditions.

Abstract

Flow coefficients v_n for n = 2, 3, 4, characterizing the anisotropic collective flow in Au+Au collisions at sqrt(s_NN) = 200 GeV, are measured relative to event planes \Psi_n determined at large rapidity. We report v_n as a function of transverse momentum and collision centrality, and study the correlations among the event planes of different order n. The v_n are well described by hydrodynamic models which employ a Glauber Monte Carlo initial state geometry with fluctuations, providing additional constraining power on the interplay between initial conditions and the effects of viscosity as the system evolves. This new constraint improves precision of the extracted viscosity to entropy density ratio eta/s.