Simulation of a (3+1)D glasma in Milne coordinates: Topological charge, eccentricity, and angular momentum

TL;DR

This paper presents a 3D glasma simulation in Milne coordinates for early-stage Au-Au collisions at 200 GeV, analyzing quantities like energy, pressure, topological charge, eccentricity, and angular momentum.

Contribution

It introduces a novel 3D glasma simulation method with detailed initial conditions accounting for nuclear structure and longitudinal effects.

Findings

Eccentricity varies with impact parameter.

Angular momentum distribution depends on collision geometry.

Topological charge fluctuations are characterized across rapidity.

Abstract

We apply the 3D glasma simulation method using Milne coordinates, proposed in our previous work [1], to the early stage of the Au-Au collisions at $\sqrt{s_{\rm NN}}=200$ GeV. The nucleus model prior to the collisions, which offers the initial condition for the 3D glasma simulation is constructed to account for the longitudinal structure of the nucleus, the finite thickness of nucleons and their random positions along the collision axis. We investigate rapidity profiles for a wide range of physical quantities of the glasma, including energy, pressure, fluctuations of topological charge, eccentricity, and angular momentum. In particular, we elucidate the behavior of eccentricity and angular momentum, which are physical quantities dependent on the geometric shape of the glasma, across a wide range of impact parameter regions.