A Scotogenic Model as a Prototype for Leptogenesis with One Single Gauge Singlet

Abstract

We investigate the potential of a minimal Scotogenic model with two additional scalar doublets and a single heavy Majorana fermion to explain neutrino masses, dark matter, and the baryon asymmetry of the Universe. In this minimal setup, Leptogenesis is purely flavored, and a second Majorana neutrino is not necessary because the Yukawa couplings of the extra doublets yield the necessary $CP$-odd phases. The mechanism we employ can also be applied to a wide range of scenarios with at least one singlet and two gauge multiplets. Despite stringent limits from the dark matter abundance, direct detection experiments, and the baryon asymmetry of the Universe, we find a parametric region consistent with all bounds which could resolve the above shortcomings of the Standard Model of particle physics. Methodically, we improve on the calculation of correlations between the mixing scalar fields given their finite width. We also present an argument to justify the kinetic equilibrium approximation for out-of-equilibrium distribution functions often used in calculations of Baryogenesis and Leptogenesis.