Related papers: Non-zero \theta_13 in models for hierarchical neut…
Best-fit values of recent global analyzes of neutrino data imply large solar neutrino mixing, vanishing U_{e3} and a non-maximal atmospheric neutrino mixing angle theta_{23}. We show that these values emerge naturally by the hypothesis of…
In the light of the recent measurement of the leptonic mixing angle $\theta_{13}$, implications of the latest mixing data have been investigated for non-minimal textures of lepton mass matrices assuming the neutrinos to be Majorana like.…
We present a model of neutrino masses combining the seesaw mechanism and strong Dirac mass hierarchy and at the same time exhibiting a significantly reduced hierarchy at the level of active neutrino masses. The heavy Majorana masses are…
We consider a Majorana neutrino mass matrix $\mathcal{M}_\nu$ with $(\mathcal{M}_\nu)_{\mu\mu} = (\mathcal{M}_\nu)_{\tau\tau} = 0$, in the basis where the charged-lepton mass matrix is diagonal. We show that this pattern for the lepton mass…
A large hierarchy of the Dirac masses can result in a small hierarchy for the low energy masses of the active neutrinos. This can happen even if the Majorana masses of right-handed neutrinos are all equal. A realistic description of the…
Motivated by effective low energy models of string origin, we discuss the neutrino masses and mixing within the context of the Minimal Supersymmetric Standard Model supplemented by a U(1) anomalous family symmetry and additional Higgs…
In contrast to the original type I seesaw mechanism that requires right-handed Majorana neutrinos at energies much higher than the electroweak scale, the so-called low scale seesaw models allow lighter masses for the additional neutrinos.…
An attempt is made to explore the possibility for deviations of solar mixing angle ($\theta_{12}$) from tri-bimaximal mixings, without sacrificing the predictions of maximal atmospheric mixing angle ($\theta_{23}=\pi/4$) and zero reactor…
We study models of neutrino masses which naturally give rise to an inverted mass hierarchy and bi-maximal mixing. The models are based on the see-saw mechanism with three right-handed neutrinos, which generates a single mass term of the…
A non-minimal approximation for effective masses of light and heavy neutrinos in the framework of a type-I seesaw mechanism with three generations of sterile Majorana neutrinos which recover the symmetry between quarks and leptons is…
If the mixing angles in each of the seesaw sectors are all small, and the neutrino masses are hierarchical, we study the conditions for large neutrino mixing using triangular matrices. In particular, the implication of the neutrino…
In the basis where the charged lepton mass matrix is diagonal, the left-handed neutrino mass matrix is invariant under the permutation of the second and third generations if, and only if, the reactor angle $\theta_{13}$ is zero and the…
A previous short analysis of the seesaw mechanism, based on quark-lepton symmetry, experimental data and hierarchical neutrino spectrum, is enlarged to include small but not zero U_{e3}, inverted mass hierarchy, and the qualitative effect…
We discuss a 331 model with three scalar triplets and neutral fermion singlets. We show that in the 331 model with right-handed neutrinos, it is possible to obtain small active neutrino masses via the double and inverse seesaw mechanisms,…
In this paper, we obtain the light neutrino masses and mixings consistent with the experiments, in the democratic texture approach. The essential ansatz is that $\nu_{Ri}$ are assumed to transform as "right-handed fields" $\bf 2_{R} +…
The left-right symmetric models (LRSM) generally include type-I and type-II induced seesaw masses as a hybrid mass for the light-active neutrinos. Assuming a particular form of Dirac-type coupling, the Majorana-type coupling in the seesaw…
We propose a simple but suggestive seesaw model with two phenomenological conjectures: three heavy (right-handed) Majorana neutrinos are degenerate in mass in the symmetry limit and three light Majorana neutrinos have the tri-bimaximal…
We consider the problem of neutrino masses and mixing within the framework of a non-minimal supersymmetric SU(5) model extended by adding a set of 1,24 chiral superfields accommodating three right-handed neutrinos. A Type I+III see-saw…
Motivated by recent results from neutrino experiments, we study the neutrino masses and mixing in the framework of a SUSY $SU(5)\times \mathbb{A}_{4} $ model. The hybrid of Type I and Type II seesaw mechanisms leads to the nonzero value of…
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…