Evolution of energy density fluctuations in A+A collisions

TL;DR

This paper investigates how initial density fluctuations in heavy-ion collisions evolve over time, potentially explaining the observed ridge structures in particle correlations at RHIC energies.

Contribution

It models the evolution of initial energy density fluctuations, represented as longitudinal tubes, through the system's thermal evolution until freeze-out.

Findings

Energy density fluctuations evolve into ridge-like structures.

Initial tube-like density profiles influence final particle correlations.

Transverse velocity and energy density profiles are characterized at various evolution stages.

Abstract

Two-particle angular correlation for charged particles emitted in Au+Au collisions at the center-of-mass of 200 MeV measured at RHIC energies revealed novel structures commonly referred to as a near-side ridge. The ridge phenomenon in relativistic A+A collisions is rooted probably in the initial conditions of the thermal evolution of the system. In this study we analyze the evolution of the bumping transverse structure of the energy density distribution caused by fluctuations of the initial density distributions that could lead to the ridge structures. We suppose that at very initial stage of collisions the typical one-event structure of the initial energy density profile can be presented as the set of longitudinal tubes, which are boost-invariant in some space-rapidity region and are rather thin. These tubes have very high energy density comparing to smooth background density distribution. The transverse velocity and energy density profiles at different times of the evolution till the chemical freeze-out (at the temperature T=165 MeV) willbe reached by the system are calculated for sundry initial scenarios.