Global quenches and correlator dynamics in de Sitter space

TL;DR

This paper develops a framework to analyze non-equilibrium quantum field dynamics after global quenches in curved spacetime, with applications to de Sitter space and implications for cosmological observables.

Contribution

It introduces a method using the Keldysh-Schwinger formalism to compute post-quench correlators in arbitrary geometries, including de Sitter space, extending previous flat-space results.

Findings

Late-time decay of quenched correlations depends on mass in de Sitter space.

The approach reproduces known relaxation in flat space and reveals new dynamics for massless fields.

Framework can incorporate non-Gaussian initial states for future cosmological studies.

Abstract

We study non-equilibrium initial states of quantum fields in curved space-time and develop a framework for describing global quenches as unitary perturbations of the initial density matrix. Using the Keldysh-Schwinger functional integral, we derive expressions for post-quench correlators in arbitrary geometries and apply the method to both Minkowski and de Sitter backgrounds. In flat space, the approach reproduces the known relaxation behaviour for massive fields and reveals qualitatively distinct dynamics in the massless case. In de Sitter space, we find that the late-time decay of quench-induced corrections depends sensitively on the mass and may influence the behaviour of cosmological observables such as the power spectrum. The framework also extends straightforwardly to non-Gaussian initial states, providing a basis for future studies of loop effects and primordial non-Gaussianities.