Thermally Fluctuating Second-Order Viscous Hydrodynamics and Heavy-Ion Collisions

TL;DR

This paper investigates how thermal noise, mandated by the fluctuation-dissipation theorem, influences viscous hydrodynamics in heavy-ion collisions, showing it affects observables like momentum eccentricity.

Contribution

It introduces thermal noise into hydrodynamic simulations of heavy-ion collisions, revealing its impact on fluctuation and average values of flow observables.

Findings

Thermal noise increases average momentum eccentricity.

Thermal fluctuations contribute significantly to event-by-event fluctuations.

Inclusion of noise alters the interpretation of collision data.

Abstract

The fluctuation-dissipation theorem requires the presence of thermal noise in viscous fluids. The time and length scales of heavy ion collisions are small enough so that the thermal noise can have a measurable effect on observables. Thermal noise is included in numerical simulations of high energy lead-lead collisions, increasing average values of the momentum eccentricity and contributing to its event by event fluctuations.