Cosmological phase transitions, gravitational waves and self-interacting dark matter in the singlet extension of MSSM

TL;DR

This paper explores how a singlet extension of the MSSM can produce a first-order phase transition and self-interacting dark matter, with potential detection via gravitational waves in upcoming experiments.

Contribution

It demonstrates the viability of a SUSY singlet model to explain dark matter and cosmological phase transitions, linking gravitational wave signals to this scenario.

Findings

First-order phase transition can occur with light dark matter below MeV.

Gravitational wave signals from phase transitions are detectable by future observatories.

Parameter space for SIDM and FOPT can be partially probed by upcoming GW experiments.

Abstract

In the minimal supersymmetric standard model (MSSM) extended by a singlet superfield, when the coupling between the singlet sector and the MSSM sector is tiny, the singlet sector can be a quasi dark sector with supersymmetry (SUSY). We investigate the cosmological phenomena in this scenario and obtain the following observations: (i) In the parameter space solving the small cosmological scale anomalies via self-interacting singlino dark matter (SIDM), a first-order phase transition (FOPT) can readily happen but requires rather light dark matter below MeV; (ii) The corresponding parameter space indicated by FOPT and SIDM can be partially covered by detecting the phase-transition gravitational waves (GWs) at the near-future projects, such as LISA, TianQin and Taiji. Therefore, the recently developed GW astronomy could be a novel probe to such a SUSY scenario.