Harmonic decomposition of three-particle azimuthal correlations at RHIC

Abstract

We present measurements of three-particle correlations for various harmonics in Au+Au collisions at energies ranging from $\sqrt{s_{\mathrm{NN}}}=7.7$ to 200 GeV using the STAR detector. The quantity $⟨\cos (m{\varphi }_1+n{\varphi }_2-(m+n){\varphi }_3)⟩$ is evaluated as a function of $\sqrt{s_{\mathrm{NN}}}$, 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.

19 pages, 15 figures, v2 : additional texts and references added