Radiative neutrino masses in the singlet-doublet fermion dark matter model with scalar singlets

Abstract

When the singlet-doublet fermion dark matter model is extended with additional ${Z}_{2}$-odd real singlet scalars, neutrino masses and mixings can be generated at the one-loop level. In this work, we discuss the salient features arising from the combination of the two resulting simplified dark matter models. When the lightest ${Z}_{2}$-odd particle is a scalar singlet, $\mathrm{Br}(\ensuremath{\mu}\ensuremath{\rightarrow}e\ensuremath{\gamma})$ could be measurable provided that the singlet-doublet fermion mixing is small enough. In this scenario, the new decay channels of vector-like fermions into scalars can also generate interesting leptonic plus missing transverse energy signals at the LHC. On the other hand, in the case of doublet-like fermion dark matter, scalar coannihilations lead to an increase in the relic density which allows one to lower the bound of doublet-like fermion dark matter.