A method for studying initial geometry fluctuations via event plane correlations in heavy ion collisions

TL;DR

This paper introduces a Fourier analysis method to measure correlations among multiple event planes in heavy ion collisions, aiding the study of initial geometry fluctuations.

Contribution

It proposes a novel Fourier-based approach to analyze event plane correlations, linking them to existing correlators and identifying new measurable correlators.

Findings

Fourier coefficients match known correlators like cos(6Phi_2-6Phi_3)

Identifies new two- and three-plane correlators with sizable magnitudes

Method demonstrated using Monte Carlo Glauber model simulations

Abstract

A method is proposed to measure the relative azimuthal angle distributions involving two or more event planes of different order in heavy ion collisions using a Fourier analysis technique. The analysis procedure is demonstrated for correlations involving two and three event planes (Phi_n, Phi_m and Phi_h). The Fourier coefficients of these distributions are found to coincide with previously proposed correlators, such as cos(6Phi_2-6Phi_3) and cos(Phi_1+2Phi_2-3Phi_3) etc, hence the method provides a natural framework for studying these correlators at the same time. Using a Monte Carlo Glauber model to simulate Au+Au collisions with fluctuating initial geometry, we are able to identify several new two- or three-plane correlators that have sizable magnitudes and should be measured experimentally.