Gravitational wave signals of electroweak phase transition triggered by dark matter

Abstract

We study in this work a scenario that the universe undergoes a two step phase\ntransition with the first step happened to the dark matter sector and the\nsecond step being the transition between the dark matter and the electroweak\nvacuums, where the barrier between the two vacuums, that is necessary for a\nstrongly first order electroweak phase transition (EWPT) as required by the\nelectroweak baryogenesis mechanism, arises at the tree-level. We illustrate\nthis idea by working with the standard model (SM) augmented by a scalar singlet\ndark matter and an extra scalar singlet which mixes with the SM Higgs boson. We\nstudy the conditions for such pattern of phase transition to occur and\nespecially for the strongly first order EWPT to take place, as well as its\ncompatibility with the basic requirements of a successful dark matter, such as\nobserved relic density and constraints of direct detections. We further explore\nthe discovery possibility of this pattern EWPT by searching for the\ngravitational waves generated during this process in spaced based\ninterferometer, by showing a representative benchmark point of the parameter\nspace that the generated gravitational waves fall within the sensitivity of\neLISA, DECIGO and BBO.\n