Gravitational Wave Emissions from First Order Phase Transitions with Two Component FIMP Dark Matter

Abstract: We explore the emissions of the Gravitational Waves (GWs) from a strong first-order ekectroweak phase transition. To this end, a dark matter model has been investigated in Feebly Interacting Massive Particle (FIMP) scenario, where the dark matter particles are produced through "freeze-in" mechanism in the early Universe and due to their very small couplings they could not attain thermal and chemical equilibrium with the Universe's thermal plasma. In this context, we extend scalar sector of Standard Model of particle physics by two additional scalar singlets whose stability is protected by an unbroken discrete $Z_2 \times Z'_2$ symmetry and they are assumed to develop no VEV after spontaneous symmetry breaking. We study the first-order phase transition within the framework of this present model. We have done both analytical and numerical computations to calculate the consequent production of GWs and then the detectabilities of such GWs have been investigated at the future space based detectors such as LISA, BBO, ALIA, DECIGO, aLIGO and aLIGO+ etc. We also find that dark matter self coupling has a considerable influence on the GW production in the present scenario.