# Constraining the initial conditions and temperature dependent transport with three-particle correlations in Au+Au collisions

## TL;DR

This paper measures three-particle correlations in Au+Au collisions at RHIC to understand the initial collision geometry and constrain models of quark-gluon plasma evolution, focusing on initial conditions and temperature-dependent transport properties.

## Contribution

It provides new three-particle mixed-harmonic correlation measurements that help constrain initial state models and temperature-dependent transport coefficients in heavy-ion collisions.

## Key findings

- Correlations reveal initial state fluctuations and longitudinal invariance breaking.
- Results favor certain hydrodynamic models over others.
- Data constrains temperature-dependent viscosity in quark-gluon plasma.

## Abstract

We present three-particle mixed-harmonic correlations $\la \cos (m\phi_a + n\phi_b - (m+n) \phi_c)\ra$ for harmonics $m,n=1-3$ for charged particles in $\sqrt{s_{NN}}=$200 GeV Au+Au collisions at RHIC. These measurements provide information on the three-dimensional structure of the initial collision zone and are important for constraining models of a subsequent low-viscosity quark-gluon plasma expansion phase. We investigate correlations between the first, second and third harmonics predicted as a consequence of fluctuations in the initial state. The dependence of the correlations on the pseudorapidity separation between particles show hints of a breaking of longitudinal invariance. We compare our results to a number of state-of-the art hydrodynamic calculations with different initial states and temperature dependent viscosities. These measurements provide important steps towards constraining the temperature dependent transport and the longitudinal structure of the initial state at RHIC.