Investigation of the linear and mode-coupled flow harmonics in Au+Au collisions at $\sqrt{\textit{s}_{NN}}$ = 200 GeV

TL;DR

This paper investigates higher-order flow harmonics in Au+Au collisions at 200 GeV, analyzing their linear and mode-coupled contributions to better understand initial conditions and medium properties.

Contribution

It provides the first detailed measurement of linear and mode-coupled flow harmonic contributions at RHIC energies, comparing results with LHC data and hydrodynamic models.

Findings

Higher-order flow harmonics include significant mode-coupled contributions.

Results show consistency with viscous hydrodynamic predictions.

Comparisons highlight differences between RHIC and LHC collision dynamics.

Abstract

Flow harmonics ($\textit{v}_{n}$) of the Fourier expansion for the azimuthal distributions of hadrons are commonly employed to quantify the azimuthal anisotropy of particle production relative to the collision symmetry planes. While lower order Fourier coefficients ($\textit{v}_{2}$ and $\textit{v}_{3}$) are more directly related to the corresponding eccentricities of the initial state, the higher-order flow harmonics ($\textit{v}_{n>3}$) can be induced by a mode-coupled response to the lower-order anisotropies, in addition to a linear response to the same-order anisotropies. These higher-order flow harmonics and their linear and mode-coupled contributions can be used to more precisely constrain the initial conditions and the transport properties of the medium in theoretical models. The multiparticle azimuthal cumulant method is used to measure the linear and mode-coupled contributions in the higher-order anisotropic flow, the mode-coupled response coefficients, and the correlations of the event plane angles for charged particles as functions of centrality and transverse momentum in Au+Au collisions at nucleon-nucleon center-of-mass energy $\sqrt{\textit{s}_{NN}}$ = 200 GeV. The results are compared to similar LHC measurements as well as to several viscous hydrodynamic calculations with varying initial conditions.