MeV scale model of SIMP dark matter, neutrino mass and leptogenesis

We consider a simple extension of the Standard Model with two singlet scalar fields and three heavy right-handed neutrinos. One of the scalar fields serves as an MeV scale dark matter and its stability is ensured by the introduction of an extra $Z_2$ symmetry. The second scalar (which is even under the $Z_2$ symmetry) generates the mass term of the scalar, contributes to the $3 \rightarrow 2$ annihilation process required for the correct relic density of the dark matter and it also contributes to the leptogenesis. The right-handed neutrinos are responsible for the generation of light neutrino masses through Type-I seesaw mechanism. The decay of the heavy right-handed neutrino can generate the lepton asymmetry which can then be converted to baryon asymmetry through sphaleron transitions.