Gravitational waves from global cosmic strings in quintessential inflation

TL;DR

This paper investigates gravitational waves produced by global cosmic strings during quintessential inflation, highlighting how symmetry breaking and restoration can generate detectable gravitational wave backgrounds that inform early universe physics.

Contribution

It models the gravitational wave background from global cosmic strings in quintessential inflation, linking the spectrum to non-minimal gravity couplings and post-inflationary energy scales.

Findings

Gravitational wave spectrum depends on the duration of the heating process.

Potential detectability of the gravitational wave background.

Provides a test for non-minimal gravity couplings and post-inflationary physics.

Abstract

The combination of non-minimal couplings to gravity with the post-inflationary kinetic-dominated era typically appearing in quintessential inflation scenarios may lead to the spontaneous symmetry breaking of internal symmetries and its eventual restoration at the onset of radiation domination. On general grounds, the breaking of these symmetries leads to the generation of short-lived topological defects that tend to produce gravitational waves until the symmetry is restored. We study here the background of gravitational waves generated by a global cosmic string network following the dynamical symmetry breaking and restoration of a $U(1)$ symmetry. The resulting power spectrum depends on the duration of the heating process and it is potentially detectable, providing a test on the existence of non-minimal couplings to gravity and the characteristic energy scale of post-inflationary physics.