# Harmonic decomposition of three-particle azimuthal correlations at RHIC

## TL;DR

This paper reports measurements of three-particle azimuthal correlations in gold-gold collisions at RHIC across various energies, revealing insights into the initial collision geometry, medium expansion, and transport properties of the quark-gluon plasma.

## Contribution

It provides detailed three-particle correlation data across multiple energies, offering new constraints on models of heavy-ion collision dynamics and medium properties.

## Key findings

- Strong $ riangle
m exteta$ dependence indicating breaking of boost invariance
- Energy-dependent changes in two-particle correlations relative to the event-plane
- Data constrains theoretical models of collision dynamics and medium properties

## Abstract

We present measurements of three-particle correlations for various harmonics in Au+Au collisions at energies ranging from $\sqrt{s_{{\rm NN}}}=7.7$ to 200 GeV using the STAR detector. The quantity $\langle\cos(m\phi_1+n\phi_2-(m+n)\phi_3)\rangle$ is evaluated as a function of $\sqrt{s_{{\rm NN}}}$, collision centrality, transverse momentum, $p_T$, pseudo-rapidity difference, $\Delta\eta$, and harmonics ($m$ and $n$). These data provide detailed information on global event properties like the three-dimensional structure of the initial overlap region, the expansion dynamics of the matter produced in the collisions, and the transport properties of the medium. A strong dependence on $\Delta\eta$ is observed for most harmonic combinations consistent with breaking of longitudinal boost invariance. Data reveal changes with energy in the two-particle correlation functions relative to the second-harmonic event-plane and provide ways to constrain models of heavy-ion collisions over a wide range of collision energies.