Related papers: Option of three pseudo--Dirac neutrinos
Symplectic flavour symmetry group Sp(n/2) (n is even) of n Majorana states does not allow for invariant Majorana masses. Only specific mass matrices with diagonal and nondiagonal elements are possible here. As a result of the spontaneous…
Light Dirac neutrino of mass of mass of the order of few eV is obtained in an $SU(2)_L\times U(1)_Y$ model with an extended Higgs sector and right-handed neutrinos. Small neutrino mass is generated at the tree level through small effective…
We show that in the minimal three generation seesaw models for neutrinos, the presence of leptonic $(L_e+L_{\mu}-L_{\tau})\times S_2$ symmetry leads to one of the right handed neutrinos remaining massless. This state can then be identified…
We derive the neutrino oscillation probabilities including sterile neutrinos by using the Dirac equation. If neutrinos have both the Dirac and the Majorana mass terms, left-handed neutrino $\nu_L$ and right-handed anti-neutrino $\nu_R^c$…
We evaluate the predictive power of the neutrino mass matrices arising from seesaw mechanism with heavy Majorana mass matrices subject to texture zero and satisfy a cyclic permutation invariant form to the solar neutrino mixing phenomena.…
We argue how pseudo-Dirac scenario for neutrinos leads to rich neutrino oscillation phenomena, including oscillation inside each generation. The pseudo-Dirac scenario is generalized by incorporating generation mixings and formulae for the…
In the conventional type-(I+II) seesaw model, the effective mass matrix of three known light neutrinos is given by M_nu = M_L - M_D M^{-1}_R M^T_D in the leading-order approximation. We propose an intriguing scenario, in which the…
New experimental results, if correct, require at least one light sterile neutrino, in addition to the three active ones, to accommodate the mass differences required to explain the solar $\nu_e$ deficit, the anomalous $\nu/e$ ratio produced…
On the basis of a seesaw-type mass matrix model for quarks and leptons, $M_f \simeq m_L M_F^{-1} m_R$, where $m_L\propto m_R$ are universal for $f=u,d,\nu$ and $e$ (up-quark-, down-quark-, neutrino- and charged lepton-sectors), and $M_F$…
If neutrinos are Dirac particles, their right-handed partners must be present in the theory. Once introduced in the Standard Model (SM), the difference between the baryon number $B$ and the lepton number $L$ can be promoted to a local…
Models with three active neutrinos and one sterile neutrino can naturally account for maximal oscillations of atmospheric neutrinos, explain the solar neutrino deficit, and accommodate the results of the LSND experiment. The models predict…
It is often said that neutrino mass is a window to a new physics beyond the standard model (SM). This is certainly true if neutrinos are Majorana particles since the SM with Majorana neutrino mass is not a complete theory. The classical…
The observed pattern of lepton mixing does not give an evidence of the seesaw. It is easier to disprove seesaw showing that one of the alternatives gives dominant contribution to the neutrino mass. We consider alternative mechanisms based…
I review promising approaches to neutrino mass models, focussing on three neutrino patterns of neutrino masses and mixing angles, and the corresponding Majorana mass matrices. I discuss the see-saw mechanism, and show how it may be applied…
We quantify the effects of light spin-zero particles with pseudoscalar couplings to leptons and scalar couplings to nucleons on the evolution of solar neutrinos. In this scenario the matter potential sourced by the nucleons in the Sun's…
We suggest that the Large Mixing Angle MSW solar solution, whose unique physical status is confidently supported by the recent results from KamLAND experiments, gets its justification in the fermion universality, interpreted for neutrinos…
We consider the see-saw mechanism for hierarchical Dirac and Majorana neutrino mass matrices m_D and M_R, including the CP violating phases. Simple arguments about the structure of the neutrino mass matrix and the requirement of successful…
We consider the Grand Unification (GU) scenario for neutrino masses which is based on the see-saw mechanism with the mass of the heaviest right handed (RH) neutrino at the GU-scale: $M_3 \sim \Lambda_{GU}$, and on the quark-lepton symmetry…
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…
A simple extension of the standard model is to introduce $n$ heavy right-handed Majorana neutrinos and preserve its $\rm SU(2)^{}_L \times U(1)^{}_Y$ gauge symmetry. Diagonalizing the $(3+n) \times (3+n)$ neutrino mass matrix, we obtain an…