# Gravitational Wave Signals of Electroweak Phase Transition Triggered by Dark Matter

## TL;DR

This paper proposes a two-step phase transition scenario involving dark matter and electroweak vacuums, which can produce detectable gravitational waves, linking dark matter properties with early universe phase transitions.

## Contribution

It introduces a novel two-step phase transition model with a tree-level barrier, compatible with dark matter constraints and capable of generating observable gravitational waves.

## Key findings

- Conditions for strongly first order electroweak phase transition identified
- Gravitational wave signals within the sensitivity of future space-based detectors
- Model consistent with dark matter relic density and detection constraints

## Abstract

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