Gravitational Waves from Phase Transitions in Scale Invariant Models

TL;DR

This paper explores gravitational wave signals from a strongly first order electroweak phase transition in scale invariant models, analyzing how radiative corrections influence the spectrum and potential detectability by future experiments.

Contribution

It introduces an extended scale invariant model with a singlet and scalar field to study GW signals and phase transition strength, highlighting the impact of radiative corrections on observables.

Findings

Detectable GW spectra are possible in both light dilaton and PRHM scenarios.

Future GW detectors like LISA and DECIGO can observe these signals.

Scenarios can be distinguished by GW observations and di-Higgs measurements.

Abstract

We investigate the properties of the gravitational waves (GWs) generated during a strongly first order electroweak phase transition (EWPT) in models with the classical scale invariance (CSI). Here, we distinguish two parameter space regions that correspond to the cases of (1) light dilaton and (2) purely radiative Higgs mass (PRHM). In the CSI models, the dilaton mass, or the Higgs mass in the PRHM case, in addition to some triple scalar couplings are fully triggered by the radiative corrections (RCs). In order to probe the RC effects on the EWPT strength and on the GW spectrum, we extend the standard model by a real singlet to assist the electroweak symmetry breaking and an additional scalar field $Q$ with multiplicity $N_Q$ and mass $m_Q$. After imposing all theoretical and experimental constraints, we show that a strongly first order EWPT with detectable GW spectra can be realized for the two cases of light dilaton and PRHM. We also show the corresponding values of the relative enhancement of the cross section for the di-Higgs production process, which is related to the triple Higgs boson coupling. We obtain the region in which the GW spectrum can be observed by different future experiments such as LISA and DECIGO. We also show that the scenarios (1) and (2) can be discriminated by future GW observations and measurements of the di-Higgs productions at future colliders.