Dark Confinement and Chiral Phase Transitions: Gravitational Waves vs Matter Representations

TL;DR

This paper investigates gravitational-wave signals from strongly coupled dark sector models with different matter representations, highlighting how these differences affect detectability by future observatories.

Contribution

It identifies how matter representations influence the strength of phase transitions and gravitational-wave signals in dark confinement and chiral symmetry breaking models.

Findings

Two-index symmetric representation yields the strongest first-order phase transition.

Significant differences in gravitational-wave signals depend on matter representations.

Higher detection probability for models with two-index symmetric fermions.

Abstract

We study the gravitational-wave signal stemming from strongly coupled models featuring both, dark chiral and confinement phase transitions. We therefore identify strongly coupled theories that can feature a first-order phase transition. Employing the Polyakov-Nambu-Jona-Lasinio model, we focus our attention on SU(3) Yang-Mills theories featuring fermions in fundamental, adjoint, and two-index symmetric representations. We discover that for the gravitational-wave signals analysis, there are significant differences between the various representations. Interestingly we also observe that the two-index symmetric representation leads to the strongest first-order phase transition and therefore to a higher chance of being detected by the Big Bang Observer experiment. Our study of the confinement and chiral phase transitions is further applicable to extensions of the Standard Model featuring composite dynamics.