Quantum quenches during inflation

TL;DR

This paper introduces a novel non-perturbative method to analyze rapid transitions during inflation by studying quantum quenches in an $O(N)$ scalar field theory in de Sitter space, revealing how the effective mass evolves and temporarily breaks symmetry.

Contribution

It develops a new technique using large-$N$ limit to study quantum quenches during inflation, providing insights into mass evolution and symmetry breaking.

Findings

Effective mass tends to recover its pre-quench value but stabilizes at a different positive asymptote.

Situations where the effective mass squared becomes temporarily negative, breaking symmetry.

Method has potential applications in cosmological scenarios.

Abstract

We propose a new technique to study fast transitions during inflation, by studying the dynamics of quantum quenches in an $O(N)$ scalar field theory in de Sitter spacetime. We compute the time evolution of the system using a non-perturbative large-$N$ limit approach. We derive the self-consistent mass equation for several physically relevant transitions of the parameters of the theory, in a slow motion approximation. Our computations reveal that the effective mass after the quench evolves in the direction of recovering its value before the quench, but stopping at a different asymptotic value, in which the mass squared is strictly positive. Furthermore, we tentatively find situations in which the effective mass squared can be temporarily negative, thus breaking the $O(N)$ symmetry of the system for a certain time, only to then come back to a positive value, restoring the symmetry. We argue the relevance of our new method in a cosmological scenario.