Phenomenology of the simplest linear seesaw mechanism

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 ( N i ) 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^±→ℓ_i^±N , N→ℓ_j^±W^∓ leads to striking lepton number violation signatures at high energies which may probe the Majorana nature of neutrinos.