The seesaw mechanism of neutrino mass generation is analysed under the following assumptions: (1) minimal seesaw with no Higgs triplets, (2) hierarchical Dirac masses of neutrinos, (3) large lepton mixing primarily or solely due to the mixing in the right-handed neutrino sector, and (4) unrelated Dirac and Majorana sectors of neutrino masses. It is shown that large mixing governing the dominant...

A four-parameter Majorana neutrino mass matrix is proposed, which is exactly diagonalizable with two mixing angles, one of which is π/4 and the other large but less than π/4. The form of this mass matrix allows seven realizations of the present data on atmospheric and solar neutrino oscillations: three have the normal hierarchy, two have the inverse hierarchy, and two have three nearly degenera...

Phenomenological implications of neutrino oscillations implied by recent experimental data on pattern of neutrino mass matrix are diss-cussed. It is shown that it is possible to have a neutrino mass matrix which shows approximate flavor symmetry; the neutrino mass differences arise from flavor violation in off-diagonal Yukawa couplings. Two modest extensions of the standard model, which can emb...

The search for possible mixing patterns of charged leptons and neutrinos is important to get clues of the origin of nearly maximal mixings, since there are some preferred bases of the lepton mass matrices given by underlying theories. We systematically examine the mixing patterns which could lead to large lepton mixing angles. We find out 37 mixing patterns are consistent with experimental data...

The cubic symmetry S 4 contains A 4 and S 3 , both of which have been used to study neutrino mass matrices. Using S 4 as the family symmetry of a complete super-symmetric theory of leptons, it is shown how the requirement of breaking S 4 at the seesaw scale without breaking supersymmetry enforces a special form of the neutrino mass matrix which exhibits maximal ν µ − ν τ mixing as well as zero ...

Stimulated by a universal seesaw mass matrix model which can successfully give quark masses and CKM matrix elements in terms of charged lepton masses, the evolution of the seesaw mass matrices is investigated. Especially, an energy scale at which the parameters characterizing between quark and lepton mass matrices are unified is evaluated. PACS: 12.15.Ff, 11.10.Hi, 12.60.-i

The renormalization group equations for the general 2 × 2, complex, neutrino mass matrix are shown to have exact, analytic solutions. Simple formulas are given for the physical mixing angle, complex phase and mass ratio in terms of their initial values and the energy scales. We also establish a (complex) renormalization invariant relating these parameters. The qualitative features of the physic...

We propose a simple texture of the neutrino mass matrix with one sterile neutrino along with the three standard ones. It gives maximal mixing angles for νe → νS and νμ → ντ oscillations or vice versa. Thus with only four parameters, this mass matrix can explain the solar neutrino anomaly, atmospheric neutrino anomaly, LSND result and the hot dark matter of the universe, while satisfying all oth...