Thermal False Vacuum Decay Is Not What It Seems

Abstract:
We study decay of a thermally excited metastable vacuum in classical field theory using real-time numerical simulations. We find a significant reduction of the decay rate compared to the prediction of the standard thermal theory. The discrepancy is due to violation of thermal equilibrium during nucleation of the critical bubble and is reduced by introducing dissipation and noise in the field equations of motion. We propose a condition to ensure thermal equilibrium throughout the nucleation process and show that it is violated in Hamiltonian dynamics of a single field. For theories with multiple fields the condition may or may not be satisfied depending on the model details.