Neutrinoless Double Beta Decay with Negligible Neutrino Mass

If the electron neutrino has an effective nonzero Majorana mass, then neutrinoless double beta decay will occur. However, the latter is possible also with a negligible neutrino mass. We show how this may happen in a simple model of scalar diquarks and dileptons. This possibility allows neutrino masses to be small and hierarchical, without conflicting with the possible experimental evidence of neutrinoless double beta decay.Comment: 9 pages, including 1 figur

A See-saw model of sterile neutrino

If the smallness of the mass of the sterile neutrino is to be explained by the see-saw mechanism, the off-diagonal entries of the mass matrix needs to be protected by some symmetry not far above the electroweak scale. We implement see-saw mechanism in a gauge model based on $SU(2)^q_L \times SU(2)^l_L \times U(1)^q_Y \times U(1)^l_Y$ un-unified gauge group which breaks to $SU(2)_L \times U(1)_Y$ at the TeV region via a two-step symmetry breaking chain. The right handed diagonal block is tied to the highest scale up to which the un-unification symmetry holds. The sterile neutrino emerges from a quark-lepton mixed representation of the un-unified group.Comment: Revised version, to appear in Phys. Lett.

Lattice simulations of the strange quark mass and Fritzsch texture

A number of numerical simulations of lattice gauge theory have indicated a low mass of strange quark in 100 MeV range at the scale of $\mu=2$ GeV. In the unquenched case, which is improved over the simulation in the quenched approximation by the inclusion of $u$ and $d$ sea quark effects, one sees a further downward trend. Here the fermion mass spectrum of the Fritzsch texture is recalculated. In a single step supersymmetric GUT with $M_X \sim 10^{16}$ GeV such values of the strange quark mass can be obtained for low values of $\tan \beta$. Experimental numbers $m^{pole}_t = 173 \pm 6$ GeV and $4.1 < m_b(m_b) < 4.4$ GeV are used in this study. Since the scenario is supersymmetric, gaugino loop diagrams contribute to the masses in addition to usual tree level Yukawa contributions. Upper bound of the mixing parameter $V_{cb}$ is taken at 0.045Comment: 11 Pages, LaTe