相关论文: Large Mixing from Small: Pseudo-Dirac Neutrinos an…
If the sterile neutrino mass matrix in an otherwise conventional see-saw model has a rank less than the number of flavors, it is possible to produce pseudo-Dirac neutrinos. For the rank 1 case, 3+2 scenarios devolve naturally, as we show by…
We consider an extension of the Standard Model with three right-handed (RH) neutrinos and a Dirac pair of extra sterile neutrinos, odd under a discrete $Z_2$ symmetry, in order to have left-right symmetry in the neutrino content and obtain…
We assume that the mass matrix of active neutrinos has hierarchical form with small mixings, similar to quark mass matrix. We show that the large mixings between $\nu_\mu$ and $\nu_\tau$ as well as between $\nu_e$ and certain combination of…
Neutrino flavor mixing is explained within the recently proposed low-scale minimal linear seesaw model of neutrino mass generation, a variant of the standard linear seesaw led by a Dirac pair of extra sterile neutrinos which is odd under a…
In the seesaw model with hierarchical Dirac masses, the neutrino mixing angle exhibits the behavior of a narrow resonance. In general, the angle is strongly suppressed, but it can be maximal for special parameter values. We delineate the…
The usual see-saw mechanism for the generation of light neutrino masses is based on the assumption that all of the flavours of right-handed (more properly, sterile) neutrinos are heavy. If the sterile Majorana mass matrix is singular, one…
It is shown that if small neutrino masses owe their origin to the conventional seesaw mechanism and the MNS mixing matrix is in the exact bimaximal form, then there exist symmetries in the theory that allow one of the righthanded neutrinos…
In addition to three active neutrinos, one or more light sterile neutrinos have been conjectured to account for the LSND, MiniBooNE and reactor antineutrino anomalies (at the sub-eV mass scale) or for warm dark matter in the Universe (at…
Neutrino is a good probe of extra dimensions. Large mixing and the apparent lack of very complicated oscillation patterns may be an indication of large couplings between the brane and a single bulk neutrino. A simple and realistic…
We study the minimal seesaw model, where two right-handed Majorana neutrinos are introduced, focusing on the CP violating phase. In addition, we take the trimaximal mixing pattern for the neutrino flavor where the charged lepton mass matrix…
Neutrinos may be pseudo-Dirac states, such that each generation is actually composed of two maximally-mixed Majorana neutrinos separated by a tiny mass difference. The usual active neutrino oscillation phenomenology would be unaltered if…
The inverse and linear seesaw scenarios are two typical extensions of the canonical seesaw mechanism, which contain much more sterile degrees of freedom but can naturally explain the smallness of three active neutrino masses at a…
Within the "pseudo-Dirac" scenario for massive neutrinos the existence of sterile neutrinos which are almost degenerate in mass with the active ones is hypothesized. The presence of these sterile neutrinos can affect the flavor composition…
We propose a simple model of the neutrino mass matrix which can explain the solar and atmospheric neutrino problems in a 3($\nu_L + \nu_R$) framework. Assuming that only two right-handed neutrinos are heavy and a Dirac mass matrix has a…
We generalize the democratic neutrino mixing Ansatz by incorporating the type-II seesaw mechanism with S(3) flavor symmetry. We find that bilarge neutrino mixing can naturally appear if the flavor democracy contribution is strongly…
We point out that the minimal seesaw model can provide a natural framework to accommodate tiny neutrino masses, while its experimental testability and notable predictiveness are still maintained. This possibility is based on the observation…
Motivated by recent hints in particle physics and cosmology, we study the realization of eV-scale sterile neutrinos within both the seesaw mechanism and flavor symmetry theories. We show that light sterile neutrinos can rather easily be…
A universal seesaw mass matrix model, which gives successful description of quark mass matrix in terms of lepton masses, yields three "sterile" neutrinos \nu^s_{i}, which compose pseudo-Dirac neutrinos \nu_{i\pm}^{ps}\simeq (\nu_{i} \pm…
We consider the possibility that sterile neutrinos exist and admit a description as unparticles; we call these {\em unsterile} neutrinos. We then examine the nature of neutrino oscillations in a model where an unsterile can mix with two…
We discuss the special class of models where nearly maximal neutrino mixing is produced through the see-saw mechanism, starting from only nearly diagonal matrices for charged leptons, Dirac neutrinos and Majorana right-handed neutrinos.