Phenomenology of the simplest linear seesaw mechanism

Abstract

The linear seesaw mechanism provides a simple way to generate neutrino masses. In addition to Standard Model particles, it includes quasi-Dirac leptons as neutrino mass mediators, and a leptophilic scalar doublet seeding small neutrino masses. Here we review its associated physics, including restrictions from theory and phenomenology. The model yields potentially detectable μ → eγ rates as well as distinctive signatures in the production and decay of heavy neutrinos (Ni) and the charged Higgs boson (H±) arising from the second scalar doublet. We have found that production processes such as e+e−→ NN, e−γ → NH− and e+e−→ H+H− followed by the decay chain {H}^{pm}to {ell}_i^{pm }N , Nto {ell}_j^{pm }{W}^{mp } leads to striking lepton number violation signatures at high energies which may probe the Majorana nature of neutrinos.