Neutrino masses and mixing angles in a supersymmetric SU (4) ⊗SU (2)L ⊗SU (2)R model Original Research Article

We consider the problem of neutrino masses and mixing angles in a supersymmetric model based on the gauge group SU(4) ⊗SU(2)L⊗SU(2)R broken at the scale MX ≈ 1016 GeV We extend a previous operator analysis of the charged lepton and quark masses and mixing angles in this model to include the neutrino sector, assuming a universal Majorana mass M for the right-handed neutrinos. The Dirac part of the neutrino matrix is then fixed by previous filtering of the ansatze of the charged fermion masses. The assumption of universal Majorana masses then leads to the physical neutrino masses and magnitudes of the elements of the leptonic mixing atrix all being predicted in terms of the single additional parameter M, whose value may be fixed by requiring that Δmeμ2 be consistent with the small angle MSW solution. Having fixed M in this way the rest of the neutrino masses and mixing angles are then predicted in terms of the ansatze which reproduce the charged fermion masses and quark mixing angles, although we emphasise again that such predictions are based on the assumption that the neutrino Majorana mass matrix is proportional to a 3×3 unit matrix. With this assumption we find that some of the ansatze imply a tau neutrino mass in the relevant range for the dark matter problem and structure formation, muon-electron neutrino mixing angles consistent with the MSW solution to the solar neutrino problem, and tau-muon neutrino mixing at a level which should soon be observed by the CHORUS and NOMAD experi