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