Rare B and K decays in a scotogenic model

A scotogenic model can radiatively generate the observed neutrino mass, provide a dark matter candidate, and lead to rare lepton flavor-violating processes. We aim to extend the model to establish a potential connection to the quark flavor-related processes within the framework of scotogenesis, enhancing the unexpectedly large branching ratio (BR) of B + → K + ν ν ¯ observed by the Belle II Collaboration. Meanwhile, the model can address tensions between some experimental measurements and standard model (SM) predictions in flavor physics, such as the muon g − 2 excess and the higher BR of B s → μ − μ + . In the model, we introduce the following dark particles: a neutral singlet Dirac-type lepton ( N ); two inert Higgs doublets ( η 1 , 2 ), with one carrying a lepton number; a charged singlet dark scalar ( χ + ) ; and a singlet vectorlike up-type dark quark ( T ). The first two entities are responsible for the radiative neutrino mass, and χ + couples to right-handed quarks and leptons and can resolve the tensions existing in muon g − 2 and B s → μ − μ + . Furthermore, the BR of B + → K + ν ν ¯ can be enhanced up to a factor of 2 compared to the SM prediction through the mediations of the dark T and the charged scalars. In addition, we also study the impacts on the K → π ν ν ¯ decays. Published by the American Physical Society 2024