Universal self-similar dynamics of relativistic and nonrelativistic field theories near nonthermal fixed points

TL;DR

This paper reveals that diverse many-body systems, both relativistic and nonrelativistic, exhibit universal self-similar dynamics near nonthermal fixed points, supported by two nonperturbative computational methods.

Contribution

It demonstrates the universality of self-similar scaling behavior across different quantum and classical systems using classical-statistical simulations and vertex-resummed kinetic theory.

Findings

Infrared scaling exponents and functions agree across systems.

Universal behavior applies to both relativistic and nonrelativistic theories.

Results provide insights into early universe dynamics and cold atom experiments.

Abstract

We investigate universal behavior of isolated many-body systems far from equilibrium, which is relevant for a wide range of applications from ultracold quantum gases to high-energy particle physics. The universality is based on the existence of nonthermal fixed points, which represent nonequilibrium attractor solutions with self-similar scaling behavior. The corresponding dynamic universality classes turn out to be remarkably large, encompassing both relativistic as well as nonrelativistic quantum and classical systems. For the examples of nonrelativistic (Gross-Pitaevskii) and relativistic scalar field theory with quartic self-interactions, we demonstrate that infrared scaling exponents as well as scaling functions agree. We perform two independent nonperturbative calculations, first by using classical-statistical lattice simulation techniques and second by applying a vertex-resummed kinetic theory. The latter extends kinetic descriptions to the nonperturbative regime of overoccupied modes. Our results open new perspectives to learn from experiments with cold atoms aspects about the dynamics during the early stages of our universe.