Phenomenology of the Generalised Scotogenic Model with Fermionic Dark Matter

Abstract: We study a simple extension of the Standard Model that accounts for neutrino masses and dark matter. The Standard Model is augmented by two Higgs doublets and one Dirac singlet fermion, all charged under a new dark global symmetry. It is a generalised version of the Scotogenic Model with Dirac fermion dark matter. Masses for two neutrinos are generated radiatively at one-loop level. We study the case where the singlet fermion constitutes the dark matter of the Universe. We study in depth the phenomenology of the model, in particular the complementarity between dark matter direct detection and charged lepton flavour violation observables. Due to the strong limits from the latter, dark matter annihilations are suppressed and the relic abundance is set by coannihilations with (and annihilations of) the new scalars if the latter and the Dirac fermion are sufficiently degenerate in mass. We discuss how different ratios of charged lepton flavour violating processes can be used to test the model. We also discuss the detection prospects of the charged scalars at colliders. In some cases these leave ionising tracks and in others have prompt decays, depending on the flavour in the final state and neutrino mass orderings.