Neutrinoless double beta decay in minimal left-right symmetric model with universal seesaw
Abstract
We present a detailed discussion on neutrinoless double beta decay (0 β β) within left-right symmetric models based on the gauge symmetry of type SU(2)L × SU(2)R × U(1)B-L as well as SU(3)L × SU(3)R × U(1)X where fermion masses including that of neutrinos are generated through a universal seesaw mechanism. We find that one or more of the right-handed neutrinos could be as light as a few keV if left-right symmetry breaking occurs in the range of a few TeV to 100 TeV. With such light right-handed neutrinos, we perform a detailed study of new physics contributions to 0 β β and constrain the model parameters from the latest experimental bound on such a rare decay process. We find that the new physics contribution to 0 β β in such a scenario, particularly the heavy-light neutrino mixing diagrams, can individually saturate the existing experimental bounds, but their contributions to total 0 β β half-life cancels each other due to unitarity of the total 6× 6 mass matrix. The effective contribution to half-life therefore, arises from the purely left and purely right neutrino and gauge boson mediated diagrams. We find that the parameter space saturating the 0 β β bounds remain allowed from the latest experimental bounds on charged lepton flavour violating decays like μ → e γ. We finally include the bounds from cosmology and supernova to constrain the parameter space of the model.