Chaotic inflation with a scalar field in non-classical states

TL;DR

This paper investigates how quantum states of a scalar field influence chaotic inflation in a flat universe, showing that a wide range of initial quantum states can lead to inflation, with some states requiring higher order corrections for accurate predictions.

Contribution

It introduces a method to analyze quantum effects of the scalar field in inflation, including non-classical states, within a semiclassical gravity framework.

Findings

Inflation can occur for many initial quantum states, including coherent and certain non-classical states.

States with zero mean field, like vacuum or thermal states, can also induce inflation but require higher order corrections.

Perturbative corrections to the coupled system are evaluated, enhancing understanding of quantum effects in inflation.

Abstract

We study chaotic inflation driven by a real, massive, homogeneous minimally coupled scalar field in a flat Robertson-Walker spacetime. The semiclassical limit for gravity is considered, whereas the scalar field is treated quantum mechanically by the technique of invariants in order to also investigate the dynamics of the system for non-classical states of the latter. An inflationary stage is found to be possible for a large set of initial quantum states, obviously including the coherent ones. States associated with a vanishing mean value of the field (such as the vacuum and the thermal) can also lead to inflation, however for such states we cannot make a definitive prediction due to the importance of higher order corrections during inflation. The results for the above coupled system are described and their corrections evaluated perturbatively.