Gravitational Waves from Composite Dark Sectors

TL;DR

This paper explores conditions under which phase transitions in composite dark sectors produce detectable gravitational waves, using a linear sigma model to analyze the dynamics and potential observability.

Contribution

It introduces a detailed analysis of gravitational-wave signals from first-order phase transitions in composite dark sectors using an extended linear sigma model with Polyakov loop effects.

Findings

Strong first-order phase transitions can occur with weak effective couplings.

Such transitions can produce gravitational waves detectable by future experiments.

The model mimics QCD-like theories with confinement-deconfinement dynamics.

Abstract

We study under which conditions a first-order phase transition in a composite dark sector can yield an observable stochastic gravitational-wave signal. To this end, we employ the Linear-Sigma model featuring $N_f=3,4,5$ flavours and perform a Cornwall-Jackiw-Tomboulis computation also accounting for the effects of the Polyakov loop. The model allows us to investigate the chiral phase transition in regimes that can mimic QCD-like theories incorporating in addition composite dynamics associated with the effects of confinement-deconfinement phase transition. A further benefit of this approach is that it allows to study the limit in which the effective interactions are weak. We show that strong first-order phase transitions occur for weak effective couplings of the composite sector leading to gravitational-wave signals potentially detectable at future experimental facilities.