The Scotogenic Model with Two Inert Doublets: Parameters Space and Electroweak Precision Tests

Abstract

In this work, we study a scotogenic extension of the Standard Model featuring two inert scalar doublets and three singlet Majorana fermions, where neutrino masses are generated radiatively at one loop. The lightest among the Majorana fermions and neutral scalars can serve as dark matter candidates. We explore the parameter space, considering theoretical constraints (perturbativity, unitarity, vacuum stability) and experimental limits (lepton flavor violation, Higgs measurements, electroweak precision observables). Our analysis identifies regions where sizable Yukawa couplings naturally arise due to constructive interference in the scalar sector. Additionally, we estimate the oblique parameters, finding that only $\Delta T$ is sensitive to charged mass splittings, while $\Delta S$ and $\Delta U$ remain small across the viable parameter space. However, 60\% of the viable parameter space is excluded by the recent CMS measurement of the $W$ boson mass, since the shift $\Delta M_W$ depends on the oblique parameters, particularly $\Delta T$ that is sensitive to scalar mass splittings.