Related papers: Generation Structure and Proton Decay Problem
We construct supersymmetric composite models of quarks and leptons from type IIA T^6/(Z_2 x Z_2) orientifolds with intersecting D6-branes. In case of T^6 = T^2 x T^2 x T^2 with no tilted T^2, a composite model of the supersymmetric SU(5)…
By adding new gauge singlets of neutral leptons, the improved versions of the 3-3-1 models with right-handed neutrinos have been recently introduced in order to explain recent experimental neutrino oscillation data through the inverse…
The quark and gluon structure of the proton has been under intense experimental and theoretical investigation for five decades. Even for the distributions of the well-studied valence quarks, challenges such as the value of the down quark to…
I review proton decay in the SUSY SU(5) GUTs assuming the mini-split SUSY breaking model. In the mini-split SUSY breaking model, the squark and slepton masses are O(10^{(2-3)}) TeV while the gaugino masses are O(1) TeV. As the result, even…
We reconsider dimension-five proton decay operators, making semi-quantitative remarks which apply to a large class of supersymmetric GUTs in which the short-distance operators are correlated with the fermion Yukawa couplings. In these GUTs,…
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…
A five dimensional model containing both left-right and quark-lepton symmetries is constructed, with the gauge group broken by a combination of orbifold compactification and the Higgs mechanism. An analysis of the gauge and scalar sectors…
A model is presented, in which fermion and vector boson states are constructed from constituents (tetrons). The model encodes all observed structures and phenomena of elementary particle physics in group theoretic items of the permutation…
A set of Grand Unified Theories based upon the gauge groups $SU(5)_\L \times SU(5)_\R$, $SO(10)_\L \times SO(10)_\R$ and $SU(4)_\C \times SU(4)_\L \times SU(4)_\R$ is explored. Several novel features distinguish these theories from the…
A definition of `dynamical generation', a hotly debated topic at present, is proposed and its implications are discussed. This definition, in turn, leads to a method allowing to distinguish in principle tetraquark and molecular states. The…
We study the correlation between proton lifetime and leptonic CP violation in a class of renormalizable supersymmetric SO(10) grand unified theories (GUTs) with {\bf 10}, {\bf 126} and {\bf 120} Higgs fields, which provides a unified…
Within a chiral $SU(15)$ gauge theory in which the Standard Model fermions are bound states of massless preons, we show that proton-decay operators are likely induced at the compositeness scale, $\Lambda_{\rm pre}$. Our estimate of the…
Possible existence of "hot-sector generations" above the well known 3 generation bound is investigated on the basis of a model of leptons and quarks, which is based on the Harari and Shupe's one. Our model predicts the existence of {\bf3 +…
We study the impact of multiple vector-like fermions in SU(5) grand unified theory (GUT). Threshold effects from extra fermions allow the observed gauge couplings to be consistently matched to a single unified gauge coupling, and typically…
Numerous recent evidences for neutrino masses have established the leptogenesis mechanism as a very natural possible explanation for the baryon asymmetry of the Universe. The explicit realization of this mechanism depends on the neutrino…
I discuss a SUSY-GUT model with a non-Abelian discrete family symmetry that explains the observed hierarchical pattern of quark and lepton masses. This $SO(10) \times \Delta(75)$ model predicts modified quadratic seesaw neutrino masses and…
Two-loop evolutions of the gauge couplings in a class of intermediate scale supersymmetric SO(10) models including the effect of third generation Yukawa couplings are studied. The unification scale, the intermediate scale and the value of…
Recently, there is a need for a general-purpose event generator of decays of an elementary particle or a hadron to a state of higher multiplicity ($N > 2$) that is simple to use and universal. We present the structure of such a library to…
We show that the see-saw neutrino mass mechanism can coexist naturally with an extended gauge symmetry (i.e. without any gauge heirarchy problem) provided that the gauge symmetry contains gauged lepton number differences. The simplest such…
A search is performed for third-generation scalar leptoquarks and heavy right-handed neutrinos in events containing one electron or muon, one hadronically decaying tau lepton, and at least two jets, using a sqrt(s) = 13 TeV pp collision…