Thermal False Vacuum Decay Is More Than It Seems

TL;DR

This paper investigates the decay rate of thermally excited false vacuums using simulations, revealing lower decay rates than standard theory predicts due to non-equilibrium effects during nucleation.

Contribution

It demonstrates the impact of thermal non-equilibrium on false vacuum decay rates and formulates conditions for equilibrium validity in weakly coupled field theories.

Findings

Decay rates are significantly lower than standard predictions at moderate temperatures.

Thermal non-equilibrium during nucleation causes the discrepancy.

At low temperatures, the standard thermal decay rate is recovered.

Abstract

We study the decay of a thermally excited metastable vacuum in classical field theory using real-time numerical simulations. We find a significantly lower decay rate than predicted by standard thermal theory at moderate temperatures, $E_b/T\sim 10$, where $E_b$ is the critical bubble energy. The discrepancy is due to the violation of thermal equilibrium during the critical bubble nucleation and is reduced if thermalization is enhanced by introduction of dissipation and thermal noise. We formulate a condition for the system to remain in equilibrium during the nucleation process and show that it is generally violated in weakly coupled field theories. Nevertheless, we argue that the violation of thermal equilibrium becomes irrelevant for the false vacuum decay rate at sufficiently low temperatures and the standard thermal rate is recovered.