A two-component vector WIMP -- fermion FIMP dark matter model with an extended seesaw mechanism

TL;DR

This paper proposes a model with two dark matter candidates, a vector WIMP and a fermion FIMP, linking neutrino masses, phase transitions, and gravitational wave signals, with implications for early Universe cosmology.

Contribution

It introduces a novel two-component dark matter model with an extended seesaw mechanism, connecting dark matter, neutrino masses, and gravitational wave signals from phase transitions.

Findings

The model's phase transition can be strong enough for electroweak baryogenesis.

Predicted gravitational waves may be detectable by future experiments.

The relic densities of WIMP and FIMP match observed dark matter abundance.

Abstract

We consider an extension of the Standard Model that explains the neutrino masses and has a rich dark matter phenomenology. The model has two dark matter candidates, a vector WIMP and a fermion FIMP, and the sum of their relic densities matches the total dark matter abundance. We extensively study the dark matter production mechanisms and its connection with the neutrino sector, together with various bounds from present and future experiments. The extra scalar field in the model may induce a first-order phase transition in the early Universe. We study the production of stochastic gravitational waves associated with the first-order phase transition. We show that the phase transition can be strong, and thus the model may satisfy one of the necessary conditions for a successful electroweak baryogenesis. Detectability of the phase transition-associated gravitational waves is also discussed.