Analyzing flow anisotropies with excursion sets in relativistic heavy-ion collisions

TL;DR

This paper introduces a shape analysis technique of excursion sets, originally used for cosmic microwave background studies, to analyze flow anisotropies in relativistic heavy-ion collisions, providing a new method to identify the event plane and quantify elliptic flow.

Contribution

The paper applies a shape analysis method of excursion sets to heavy-ion collision data, offering a novel approach to measure flow anisotropies and determine the event plane.

Findings

Angles with maximum distribution differences identify the event plane.

The magnitude of distribution differences correlates with elliptic flow strength.

The technique successfully distinguishes anisotropic flow patterns.

Abstract

We show that flow anisotropies in relativistic heavy-ion collisions can be analyzed using a certain technique of shape analysis of excursion sets recently proposed by us for CMBR fluctuations to investigate anisotropic expansion history of the universe. The technique analyzes shapes (sizes) of patches above (below) certain threshold value for transverse energy/particle number (the excursion sets) as a function of the azimuthal angle and rapidity. Modeling flow by imparting extra anisotropic momentum to the momentum distribution of particles from HIJING, we compare the resulting distributions for excursion sets at two different azimuthal angles. Angles with maximum difference in the two distributions identify the event plane, and the magnitude of difference in the two distributions relates to the magnitude of momentum anisotropy, i.e. elliptic flow.