Nonequilibrium quantum fields from first principles

TL;DR

This paper discusses recent advances in nonequilibrium quantum field theory, highlighting analytical and numerical methods that reveal new phenomena like prethermalization and improve understanding of high-energy physics and cosmology.

Contribution

It introduces first-principles approaches, including 2PI functionals and stochastic lattice simulations, to study far-from-equilibrium dynamics in quantum fields.

Findings

Identification of prethermalization phenomena

Validation of lattice stochastic quantization methods

Clarification of the validity range of semi-classical approaches

Abstract

Calculations of nonequilibrium processes become increasingly feasable in quantum field theory from first principles. There has been important progress in our analytical understanding based on 2PI generating functionals. In addition, for the first time direct lattice simulations based on stochastic quantization techniques have been achieved. The quantitative descriptions of characteristic far-from-equilibrium time scales and thermal equilibration in quantum field theory point out new phenomena such as prethermalization. They determine the range of validity of standard transport or semi-classical approaches, on which most of our ideas about nonequilibrium dynamics were based so far. These are crucial ingredients to understand important topical phenomena in high-energy physics related to collision experiments of heavy nuclei, early universe cosmology and complex many-body systems.