Primordial Gravitational Waves from Inflation and Preheating

TL;DR

This paper discusses the origins, characteristics, and potential detection methods of primordial gravitational wave backgrounds generated during inflation, preheating, and symmetry-breaking scenarios, highlighting their unique spectral features.

Contribution

It provides a detailed analysis of the spectra of gravitational waves from preheating, especially from cosmic string formation, and evaluates their detectability via CMB polarization.

Findings

Distinct spectral features for each gravitational wave background.

Identification of extra peaks in the spectrum from preheating with cosmic strings.

Assessment of the prospects for detecting these backgrounds with future CMB experiments.

Abstract

There are at least three cosmic backgrounds of primordial gravitational waves coming from inflation: those produced during inflation and associated with the stretching of quantum modes; those produced at the violent stage of preheating after inflation; and those associated with the self-ordering of Goldstone modes if inflation ends via a global symmetry breaking scenario, like in hybrid inflation. Each background has its own characteristic spectrum with specific features. We describe in detail the origin of extra peaks in the PGW background from preheating in the case in which inflation ends with the formation of cosmic strings due to an Abelian Higgs model after hybrid inflation. We then discuss the prospects for detecting each gravitational wave background, and distinguishing between them with a very sensitive probe, the local B-mode of the cosmic microwave background polarization.