TeV scale leptogenesis, inflaton dark matter, and neutrino mass in a scotogenic model

Abstract

We consider the scotogenic model, where the standard model (SM) is extended by a scalar doublet and three $Z_2$ odd SM-singlet fermions ($N_i$, $i=1,2,3$), all odd under an additional $Z_2$ symmetry, as a unifying framework for simultaneous explanation of inflation, dark matter, baryogenesis and neutrino mass. The inert doublet is coupled nonminimally to gravity and forms the inflaton. The lightest neutral particle of this doublet later becomes the dark matter candidate. Baryogenesis is achieved via leptogenesis by the decay of $N_1$ to SM leptons and the inert doublet particles. Neutrino masses are generated at the one-loop level. Explaining all these phenomena together in one model is very economic and gives us a new set of constraints on the model parameters. We calculate the inflationary parameters like spectral index, tensor-to-scalar ratio and scalar power spectrum, and find them to be consistent with the Planck 2018 constraints. We also do the reheating analysis for the inert doublet decays/annihilations to relativistic, SM particles. We find that the observed baryon asymmetry of the Universe can be obtained and the sum of light neutrino mass bound can be satisfied for the lightest $Z_2$ odd singlet fermion of mass around 10 TeV, dark matter in the mass range 1.25--1.60 TeV, and the lepton number violating quartic coupling between the SM Higgs and the inert doublet in the range of $6.5\times10^{-5}$ to $7.2\times 10^{-5}$.