Nonequilibrium Quantum Scalar Fields in Cosmology

TL;DR

This paper develops a functional Schrödinger-picture approach to analyze nonequilibrium quantum scalar fields in curved spacetime, explicitly constructing the Fock space and calculating key quantum correlations in de Sitter space.

Contribution

It introduces a novel application of the generalized invariant method to quantum fields in curved spacetime, providing explicit constructions and calculations.

Findings

Exact quantum states for scalar fields in de Sitter space

Explicit construction of the Fock space in curved spacetime

Evaluation of two-point and correlation functions

Abstract

We elaborate further the functional Schr\"{o}dinger-picture approach to the quantum field in curved spacetimes using the generalized invariant method and construct explicitly the Fock space, which we relate with the thermal field theory. We apply the method to a free massive scalar field in the de Sitter spacetime, and find the exact quantum states, construct the Fock space, and evaluate the two-point function and correlation function.