# Gravitational wave signatures from an extended inert doublet dark matter model

## TL;DR

This paper explores a dark matter model involving an inert doublet and a singlet scalar, analyzing the resulting gravitational wave signatures from early Universe phase transitions and their detectability with future observatories.

## Contribution

It introduces an extended inert doublet dark matter model with a singlet scalar and studies its gravitational wave signatures from electroweak phase transitions.

## Key findings

- First-order electroweak phase transition occurs in the model.
- Predicted gravitational wave signals are within the sensitivity of future detectors.
- The model provides a viable dark matter candidate compatible with current constraints.

## Abstract

We consider a particle dark matter model by extending the scalar sector of the Standard Model by an additional SU(2) scalar doublet which is made "inert" (and stable) by imposing a discrete $Z_2$ symmetry under which the additional scalar doublet is odd (and the SM is even) and it does not develop any vacuum expectation value (VEV). The lightest inert particle (LIP) of this inert doublet model (IDM) can be a viable candidate for Dark Matter. The IDM model is further extended by an additional singlet scalar which is also even under $Z_2$ and develop a VEV on spontaneous symmetry breaking. This additional scalar singlet mixes with SM Higgs and on diagonalisation of the mass matrix two CP even scalar eigenstates are obtained one of which is attributed to the physical Higgs (with mass 125.09 GeV). The LIP is the dark matter candidate in the extended model. For such a particle dark matter model we explore the first-order electroweak phase transition and the consequent production of Gravitational Waves (GW) at that epoch of the early Universe and calculate the intensities and frequencies for such waves. We then investigate the detection possibilities of such GWs at the future spaceborne primordial GW detectors such as eLISA, BBO, ALIA, DECIGO, U-DECIGO and ground-based detector aLIGO.