Related papers: Majorana Physics Through the Cabibbo Haze
We introduce three right-handed Majorana neutrinos and combine the type-I seesaw and inert doublet mechanisms. The resultant (active) neutrino mass matrix is divided into rank=1 and =2 parts with different energy scales. The different…
We extend the Standard Model (SM) by adding a pair of fermionic SU(2)-doublets with opposite hypercharge and a fermionic SU(2)-triplet with zero hypercharge. We impose a discrete Z_2-symmetry that distinguishes the SM fermions from the new…
We extend the Standard Model by adding a second Higgs doublet and a right-handed neutrino singlet with a heavy Majorana mass term. In this model, there are one heavy and three light Majorana neutrinos with a mass hierarchy m_3 >> m_2 >> m_1…
The structure of the Cabibbo-Kobayashi-Maskawa (CKM) matrix is analyzed from the standpoint of a composite model. A model is constructed with three families of quarks, by taking tensor products of sufficient numbers of spin-1/2…
Quark-lepton symmetry has been shown to be inconsistent with baryogenesis via leptogenesis in natural schemes of the see-saw mechanism. Within the phenomenological approach of textures, we relax this strict symmetry and propose weaker…
We propose a predictive model based on the $SU(3)_C\times SU(3)_L\times U(1)_X$ gauge symmetry, which is supplemented by the $D_4$ family symmetry and several auxiliary cyclic symmetries whose spontaneous breaking produces the observed SM…
Unlike the standard model where neutrino masses can be made arbitrarily small, we find in the minimal left-right symmetric model that Dirac type Yukawa coupling $h_D \sim 10^{-4.2}$ for $\nu_\tau$ is generated from charged fermion Yukawa…
Family symmetry could explain large mixing of the atmospheric neutrinos. The same symmetry could explain why the flavor changing current processes in supersymmetric standard models can be so suppressed. It also may be able to explain why…
Motivated by the Super-Kamiokande atmospheric neutrino data, we discuss possible textures for Majorana and Dirac neutrino masses within the see-saw framework. The main purposes of this paper are twofold: first to obtain intuition from a…
We desribe in detail a Z_6 orbifold compactification of the heterotic E_8 x E_8 string which leads to the (supersymmetric) standard model gauge group and matter content. The quarks and leptons appear as three 16-plets of SO(10), two of…
The radiative type-I seesaw has been already implemented to explain the lightness of Majorana neutrinos with both Majorana and Dirac heavy fermions, and the lightness of Dirac neutrinos with Dirac heavy fermions. In this work we present a…
A non-supersymmetric grand unified theory can exhibit a "radiative fermion mass hierarchy", in which the heavier quarks and leptons get mass at tree level and the lighter ones get mass from loop diagrams. Recently the first predictive model…
We realize a supersymmetric trinification model with three families of $({\bf 27}_{\rm tri}+{\bf 27}_{\rm tri} +\bar{\bf 27}_{\rm tri})$ by the $Z_3$ orbifold compactification with two Wilson lines. It is possible to break the trinification…
We consider a supersymmetric SO(10) model with a SU(3) symmetry of flavour in which fermion masses emerge via the see-saw mixing with superheavy fermions in 16+16bar representations. In this model the dangerous D=5 operators of proton decay…
We give a general analysis of neutrino mixing in the seesaw mechanism with three flavors. Assuming that the Dirac and u-quark mass matrices are similar, we establish simple relations between the neutrino parameters and individual Majorana…
We discuss the ordinary, non-supersymmetric SO(10) as a theory of fermion masses and mixings. We construct two minimal versions of the Yukawa sector based on $\bar{126}_H $ and either $10_H$ or $120_H$. The latter case is of particular…
The observed neutrino mixing, having a near maximal atmospheric neutrino mixing angle and a large solar mixing angle, is close to tri-bi-maximal. We argue that this structure suggests a family symmetric origin in which the magnitude of the…
We consider an existing framework of models where the neutrino Dirac and Majorana mass terms are related, and clarify how the mass structures interact through the type I seesaw mechanism, producing exact tri-bi-maximal mixing for the…
We suggest a model which addresses both the fermion mass hierarchy problem and the family problem in two-layer warped extra dimensions. In this model, 3 family fermions in 4 dimensions (4D) generate from 1 family in two-layer warped 6D by…
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,…