Thermal fluctuations on the freeze-out surface of heavy-ion collisions and their impact on particle correlations

TL;DR

This paper investigates how thermal fluctuations in fluid dynamic fields during heavy-ion collisions influence particle momentum distributions and correlations, revealing potential experimental signatures of these fluctuations.

Contribution

It introduces a generalized kinetic freeze-out model incorporating thermal fluctuations, leading to specific two-body momentum correlations not previously accounted for.

Findings

Thermal fluctuations cause a diffusion of the near-side peak in charge correlations.

Variances in chemical potentials influence angular correlation structures.

The study suggests experimental avenues to detect thermal fluctuation effects.

Abstract

Particle momentum distributions originating from a quark-gluon plasma as produced in high-energy nuclear collisions can be influenced by thermal fluctuations in fluid dynamic fields. We study this effect by generalizing the commonly used kinetic freeze-out prescription by allowing for small fluctuations around an average in fluid velocity, chemical potentials and temperature. This leads to the appearance of specific two-body momentum correlations. Combining a blast-wave parametrization of the kinetic freeze-out surface with the thermal correlation functions of an ideal resonance gas, we perform an exploratory study of angular net-charge correlations induced by thermal fluctuations around vanishing chemical potential. We note a diffusion of the near-side peak around $\Delta y=\Delta\phi=0$ induced by variances of different chemical potentials, which could be investigated experimentally.