The Effect of Non-minimally Coupled Scalar Field on Gravitational Waves from First-order Vacuum Phase Transitions

TL;DR

This paper studies how a non-minimally coupled scalar field influences gravitational wave signals from first-order vacuum phase transitions, revealing that such coupling can significantly alter the gravitational wave power spectrum.

Contribution

It introduces a model incorporating non-minimal scalar coupling and demonstrates its impact on gravitational wave spectra through numerical simulations.

Findings

Non-minimal coupling affects gravitational wave power spectrum.

Modification leads to discernible changes in gravitational wave energy density.

Initial phase dynamics are notably influenced by the coupling.

Abstract

We investigate first-order vacuum phase transitions in the presence of a non-minimally coupled scalar field starting with the coupling effect on the initial dynamics of phase transitions by defining an effective potential for the scalar field and then performing three dimensional numerical simulations to observe any possible distinction in gravitational wave power spectrum. Although we give a description of the model with the expanding background, in this particular paper, we exclude the scale factor contribution since we primarily focus on the immediate impact of the non-minimal coupling at initial phases of the transition. Even in this case we found that this modification has discernible effect on the power spectrum of the gravitational wave energy density.