Anisotropic distributions in a multi-phase transport model

TL;DR

This paper uses the AMPT model to study the relationship between initial spatial anisotropies and final flow coefficients in heavy ion collisions, revealing fluctuation behaviors and correlations that match experimental data.

Contribution

It demonstrates that the AMPT model accurately reproduces flow fluctuations and proposes the Elliptic-Power function as a suitable probability density for anisotropy distributions.

Findings

AMPT accounts for observed elliptic flow fluctuations.

Elliptic-Power function fits the event-by-event anisotropy distributions.

Non-zero correlations between different harmonic planes are observed.

Abstract

With A Multi-Phase Transport (AMPT) model we investigate the relation between the magnitude, fluctuations and correlations of the initial state spatial anisotropy $\varepsilon_{n}$ and the final state anisotropic flow coefficients $v_{n}$ in Au+Au collisions at $\sqrt{s_{_{\rm NN}}}=$ 200 GeV. It is found that the relative eccentricity fluctuations in AMPT account for the observed elliptic flow fluctuations, in agreement with measurements of the STAR collaboration. In addition, the studies based on 2- and multi-particle correlations and event-by-event distributions of the anisotropies suggest that the Elliptic-Power function is a promising candidate of the underlying probability density function of the event-by-event distributions of $\varepsilon_{n}$ as well as $v_{n}$. Furthermore, the correlations between different order symmetry planes and harmonics in the initial coordinate space and final state momentum space are presented. Non-zero values of these correlations have been observed. The comparison between our calculations and data will, in the future, shed new insight into the nature of the fluctuations of the Quark-Gluon Plasma produced in heavy ion collisions.