Beyond freeze-in: Dark Matter via inverse phase transition and gravitational wave signal

Understand

We propose a novel scenario of Dark Matter production naturally connected with generation of gravitational waves.

• Dark Matter is modelled as a real scalar, which interacts with the hot primordial plasma through a portal coupling to another scalar field.
• For a particular sign of the coupling, this system exhibits an inverse second order phase transition.
• The latter leads to an abundant Dark Matter production, even if the portal interaction is so weak that the freeze-in mechanism is inefficient.