Related papers: (Pseudo) Dirac neutrino masses in Supergravity
An extension of the Standard Model (SM) is studied in which two right-handed (RH) neutrinos per generation are incorporated, but considering the hypothesis of the symmetry of lepton and quark contents in order to deprive the number of RH…
We briefly review the neutrino mass generation mechanism in supersymmetry with Bilinear R-Parity Violation in Minimal Supergravity and Anomaly Mediated Supersymmetry Breaking.
After the electroweak symmetry breaking, we can write down two types of mass for the Standard Model neutrinos, Dirac or Majorana. It is often said that both types of mass cannot be distinguished in neutrino oscillation phenomena. This is in…
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…
If neutrinos are truly Dirac fermions, the smallness of their masses may still be natural if certain symmetries exist beyond those of the standard model of quarks and leptons. We perform a systematic study of how this may occur at tree…
We consider various possibilities for generating neutrino masses in supersymmetric models with an additional U(1)' gauge symmetry. One class of models involves two extra U(1)' x U(1)'' gauge symmetries, with U(1)'' breaking at an…
The Standard Model (SM) with one right-handed neutrino per generation is revisited with presymmetry being the global $U(1)_{B-L}$ symmetry of an electroweak theory of leptons and quarks with initially postulated symmetric fractional…
The oscillations of pseudo-Dirac neutrinos in matter are discussed and applied to the solar neutrino problem. Several scenarios such as both $\nu_e$ and $\nu_{\mu}$ being pseudo-Dirac and only $\nu_e$ or $\nu_{\mu}$ being pseudo-Dirac are…
Specific class of textures for the Dirac and Majorana mass matrices in the seesaw model leading to a pair of almost degenerate neutrinos is discussed. These textures can be obtained by imposing a horizontal $U(1)$ symmetry. A specific model…
We propose an extension of the standard model, in which neutrinos are Dirac particles and their tiny masses originate from a one-loop radiative diagram. The new fields required by the neutrino mass-generation also accommodate the…
General classes of mechanisms for generating small neutrino masses are surveyed from a top-down (superstring) perspective. In particular, string constructions have motivated various possibilities involving higher-dimensional operators,…
We aim to explain the nature of neutrinos using Peccei-Quinn symmetry. We discuss two simple scenarios, one based on a type-II Dirac seesaw and the other in a one-loop neutrino mass generation, which solve the strong CP problem and…
We show that, in $U(1)_R$-symmetric supersymmetric models, the bino and its Dirac partner (the singlino) can play the role of right-handed neutrinos and generate the neutrino masses and mixing, without the need for traditional bilinear or…
Dirac leptogenesis, in which neutrinos are purely Dirac and develop small but nonzero effective masses without the aid of the see-saw mechanism, provides an interesting alternative to the standard leptogenesis picture. Here we review the…
Based on experimental discovery that the mass-square of neutrino is negative, a quantum equation for superluminal neutrino is proposed in comparison with Dirac equation and Dirac equation with imaginary mass. A virtual particle may also be…
Quasi-Dirac neutrinos are obtained when the Lagrangian density of a neutrino mass model contains both Dirac and Majorana mass terms, and the Majorana terms are sufficiently small. This type of neutrinos introduces new mixing angles and mass…
We develop a class of left-right symmetric theories based on the gauge group $SU(3)_c \times SU(2)_L \times SU(2)_R \times U(1)$ with a generalized seesaw mechanism for generating the charged fermion masses. Neutrinos are naturally Dirac…
Neutrino masses arise via a seesaw mechanism and its mass hierarchy, with assumption that heavy Majorana neutrino mass matrix subject to $\mu-\tau$ symmetry and invariant under a cyclic permutation, are evaluated. Within this scenario, the…
We study a mechanism where tiny neutrino masses arise only from radiative contribution in a supersymmetric model. In each generation, the tree-level light neutrino mass is rotated away by introducing a second SM singlet $s_{L}$ that forms a…
We discuss how Dirac neutrinos can naturally be generated in supersymmetry and how they allow for an Affleck-Dine leptogenesis scenario, in which a left-right asymmetry is generated in the sneutrino sector, the left part of which is…