Eccentricity distributions in nucleus-nucleus collisions

TL;DR

This paper introduces the Elliptic Power distribution, a new two-parameter model for initial eccentricity in nucleus-nucleus collisions, providing better fits across all centralities compared to previous models.

Contribution

The paper presents the Elliptic Power distribution as a novel parametrization that improves modeling of eccentricity distributions in nuclear collisions.

Findings

Fits Monte Carlo models across all centralities

Outperforms Bessel-Gaussian distribution for peripheral collisions

Provides a more accurate description of eccentricity fluctuations

Abstract

We propose a new parametrization of the distribution of the initial eccentricity in a nucleus-nucleus collision at a fixed centrality, which we name the Elliptic Power distribution. It is a two-parameter distribution, where one of the parameters corresponds to the intrinsic eccentricity, while the other parameter controls the magnitude of eccentricity fluctuations. Unlike the previously used Bessel- Gaussian distribution, which becomes worse for more peripheral collisions, the new Elliptic Power distribution fits several Monte Carlo models of the initial state for all centralities.