Related papers: Naturalness and the Neutrino Matrix
Extensions of the Standard Model with additional U(1) symmetries can describe the hierarchy of fermion masses and mixing angles, including neutrinos. The neutrino masses and mixings are determined up to a discrete ambiguity corresponding to…
The observed quark hierarchies suggest a simple family symmetry. Generalized to leptons through grand-unified quantum numbers, it produces a neutrino mixing matrix with order-one \nu_{\mu} - \nu_{\tau} mixing, and order-\lambda^3 \nu_e -…
We propose a realistic model with Majorana neutrinos in the framework of unifying the three generations of fermions by point interactions in an extra dimension. This model can simultaneously explain the origin of fermion generations,…
Type I and type II seesaw contributions to the mass matrix of light neutrinos are inherently related if left-right symmetry is realized at high energy scales. We investigate implications of such a relation for the interpretation of neutrino…
The existence of neutrino mass and mixing is a strong pointer towards physics beyond the standard model. An overview of the possibility of having neutrino masses in supersymmetric theories is attempted here. Some of the recent works…
The phenomenon of neutrino oscillations is studied usually as a mixing between the flavor neutrinos and the neutrinos having a definite mass. The mixing angles and the mass eigenvalues are treated independently in order to accommodate the…
In the framework of a minimal extension of the SM, where the only additional fields are three right-handed neutrinos, we suggest that the charged lepton, the Dirac neutrino and the right-handed Majorana neutrino mass matrices are all, to…
Seesaw mechanism appears to be the simplest and most appealing way to understand small neutrino masses observed in recent experiments. It introduces three right handed neutrinos with heavy masses to the standard model, with at least one…
A natural solution to the fermion mass hierarchy problem suggests the existence of a partially conserved chiral symmetry. We show that this can lead to a reasonably natural solution to the solar and atmospheric neutrino problems without…
Systematic analyses of the textures arising in lepton mass matrices have been carried out using unitary transformations and condition of naturalness for the Dirac and Majorana neutrino possibilities. It is observed that the recent three…
We propose a predictive lepton model under a modular $S_4$ symmetry, where the neutrino mass matrix arises from a radiative seesaw at one-loop level. The tree-level mass matrix is forbidden by well-assigned modular weights, which also play…
We introduce a new parametrization of the MNS lepton mixing matrix which separates the hierarchical Grand Unified relations among quarks and leptons. We argue that one large angle stems from the charged leptons, the other from the seesaw…
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…
We consider phenomenologically allowed structures of the neutrino mass matrix in the case of three light neutrino species. Constraints from the solar, atmospheric and reactor neutrino experiments as well as those from the neutrinoless…
The configuration of the three neutrino masses can take two forms, known as the normal and inverted hierarchies. We compute the Bayesian evidence associated with these two hierarchies. Previous studies found a mild preference for the normal…
Status of determination of the neutrino masses and mixing is formulated and possible uncertainties, especially due to presence of the sterile neutrinos, are discussed. The data hint an existence of special ``neutrino'' symmetries. If not…
We study a minimal one-loop radiative mechanism for generating small Majorana neutrino masses in inverse seesaw extensions of the Standard Model with two singlet fermions per family. The new feature of this radiative mechanism is that the…
We propose a type II upgrade of type I see-saw models leading to new classes of models where partially degenerate neutrinos are as natural as hierarchical ones. The additional type II contribution to the neutrino mass matrix, which…
We demonstrate that, for every grand unified model based on a conventional type I seesaw mechanism leading to a normal light neutrino mass hierarchy, one can easily generate a corresponding model with an inverted hierarchy which yields the…
The flavor structure of quarks and leptons is not yet fully understood, but it hints a more fundamental theory of non-universal generations. We therefore propose a simple extension of the Standard Model by flipping (i.e., enlarging) the…