Origin of neutrino masses, dark matter, leptogenesis, and inflation in a seesaw model with triplets

Abstract

We consider a new physics model, where the Standard Model (SM) is extended by hyperchargeless $Y=0$ triplet fermions and a Higgs triplet with hypercharge $Y=2$. The first two generation fermion triplets are even under the ${Z}_{2}$ transformation. In contrast, the third fermion triplet and scalar triplet are odd under the same ${Z}_{2}$ transformation. It is a unifying framework for the simultaneous explanation of neutrino mass and mixing, dark matter, baryogenesis, inflation, and reheating temperature of the Universe. The two ${Z}_{2}$ even neutral fermions explain the neutrino low energy variables, whereas the third one can serve as a viable dark matter candidate, explaining the exact relic density. The scalar triplet is coupled nonminimally to gravity and forms the inflaton. We calculate the inflationary parameters and find them consistent with the new Planck-2018 constraints. We also do the reheating analysis for the inflaton decays/annihilations to relativistic SM particles. The triplet fermions associated with ${Z}_{2}$ even sector can provide the observed baryon asymmetry of the Universe at the TeV scale.