Role of quantum fluctuations in a system with strong fields

TL;DR

This paper investigates how quantum fluctuations influence the evolution of a classical field theory, specifically a scalar $^4$ model, revealing their role in driving the system towards ideal hydrodynamics in heavy-ion collision simulations.

Contribution

It introduces a detailed analysis of quantum fluctuations in a scalar field model coupled to an external source, elucidating their impact on the system's relaxation to hydrodynamic behavior.

Findings

Quantum fluctuations significantly alter the evolution of the scalar field.

The system evolves towards ideal hydrodynamics due to quantum effects.

Modified initial spectra influence the relaxation process.

Abstract

In this work we study how quantum fluctuations modify the quantum evolution of an initially classical field theory. We consider a scalar $\phi^4$ theory coupled to an external source as a toy model for the Color Glass Condensate description of the early time dynamics of heavy-ion collisions. We demonstrate that quantum fluctuations considerably modify the time evolution driving the system to evolve in accordance with ideal hydrodynamics. We attempt to understand the mechanism behind this relaxation to ideal hydrodynamics by using modified initial spectra and studying the particle content of the theory.