Neutrino Mass Scenario Research Articles

Reconciling present neutrino puzzles: Sterile neutrinos as mirror neutrinos.

We suggest that recent neutrino puzzles that are the solar and atmospheric neutrino deficits as well as the possible neutrino oscillations reported by the LSND experiment and the possibility of massive neutrinos providing the hot component of the cosmological dark matter, can all be naturally explained by assuming existence of a mirror world described by an ``electroweak'' gauge symmetry $[SU(2)\times U(1)]'$, with the breaking scale larger by about factor of 30 than the scale of the standard $SU(2)\times U(1)$ model. An interesting aspect of this model is that the sterile neutrinos arise from the hidden mirror sector of the theory and thus their lightness is more natural than in the usual neutrino mass scenarios. The needed pattern of the neutrino mass matrix in this model is obtained by assuming a conserved ZKM-type global lepton number $\bar L=L_e+L_\mu-L_\tau$, which is violated by Planck scale effects. One implication of our proposal is that bulk of the dark matter in the universe is a warm dark matter consisting of few KeV mass particles rather than the 100 GeV range particles of the currently popular cold dark matter scenarios.

Massive neutrinos and right-handed weak currents in double beta decay.

The contributions of right-handed weak currents in neutrinoless double beta decay are studied taking explicitly into account the mass corrections to the intermediate neutrino propagator. Due to these corrections the right-handed currents become effective even if all neutrinos are light (${\mathit{m}}_{\ensuremath{\nu}}$>10 MeV). Explicit expressions for the neutrino-momentum integrals and the decay half-life are derived. As an example two neutrino-mass scenarios containing the hypothetical 17-keV neutrino are discussed. The experimental half-life of the $^{76}\ensuremath{\rightarrow}^{76}$Se decay is used to obtain an upper limit for a new kind of effective right-handed coupling within the two scenarios.

A novel scenario for neutrino masses in superstring-inspired GUT models

It is shown that the usual “super-suppression” of the standard neutrino masses in the context of the SU(4) ⊗ O (4) and the flipped SU (5) ⊗ U (1) models may be avoided in the presence of large VEVs of order M GUT for the right-handed sneutrinos, which have been introduced as a means to improve the mass relations between the down-type quarks and the charged leptons in the first of the two models.