Related papers: Proton Lifetime from SU(5) Unification in Extra Di…
SU(5) $\otimes$ SU(5) provides a minimal grand unification scheme for fermions and gauge forces if there are vector-like quarks and leptons in nature. We explore the gauge coupling unification in a non-supersymmetric model of this type, and…
We consider supersymmetric unification based on the gauge symmetry SU(3)_C\times SU(3)_L\times SU(3)_R supplemented by an anomalous U(1)_A gauge symmetry. Realistic fermion masses and mixings are realized, including large mixings in the…
We present our best estimates of the uncertainties due to heavy particle threshold corrections on the unification scale $M_U$, intermediate scale $M_I$ and coupling constant Alpha_U in the minimal non-supersymmetric SO(10) models. Using…
We calculate the proton lifetime in an SO(10) supersymmetric grand unified theory [SUSY GUT] with U(2) family symmetry. This model fits the low energy data, including the recent data for neutrino oscillations. We discuss the predictions of…
We discuss baryon and lepton violation in the context of a simple 5-dimensional grand unified model, based on the orbifold S^1/(Z_2 x Z_2'). While gauge and Higgs degrees of freedom live in the bulk, matter is located on the boundaries of…
Product group unification is an attractive alternative to simple grand unification. It solves the infamous doublet-triplet splitting problem and the dimension-5 proton decay problems without introducing any fine-tuning. Furthermore, the…
We present phenomenological aspects of the simplest realistic SU(5) grand unified theory--the theory with the 5, 15, and 24 dimensional representations in the Higgs sector. We show that a successful gauge coupling unification sets…
We discuss proton decay in a recently proposed model of supersymmetric hybrid inflation based on the gauge symmetry $SU(4)_c \times SU(2)_L \times SU(2)_R$. A $U(1)\, R$ symmetry plays an essential role in realizing inflation as well as in…
We consider proton decay and $g_\mu - 2$ in flipped SU(5) GUT models. We first study scenarios in which the soft supersymmetry-breaking parameters are constrained to be universal at some high scale $M_{in}$ above the standard GUT scale…
It is noted that one is now in possession of a set of facts, which may be viewed as the matching pieces of a puzzle ; in that all of them can be resolved by just one idea - that is grand unification. These include : (i) the observed…
In a model of supersymmetric SU(5) Grand Unification with a spatial dimension described by the orbifold $S^1/(Z_2 \times Z_2')$, proton decay is naturally suppressed at all orders. This is achieved by a suitable implementation of the…
Semi-simple unification is one of a model which naturally solves two difficulties in the supersymmetric grand unification theory: doublet-triplet splitting problem and suppression of dimension 5 proton decay. We analyzed the dimension 6…
Dimension-five operators for nucleon decays are suppressed in the modified missing doublet (MMD) model in the supersymmetric SU(5) grand unification. We show that nonrenormalizable interactions decrease the unification scale in the MMD…
Giving up the solutions to the fine-tuning problems, we propose the non-supersymmetric flipped $SU(5)\times U(1)_X$ model based on the minimal particle content principle, which can be constructed from the four-dimensional $SO(10)$ models,…
Since the main experimentally testable prediction of grand unified theories is the instability of the proton, precise determination of the proton lifetime for each particular model is desirable. Unfortunately, the corresponding computation…
Dark matter candidates and proton decay in a class of models based on the AdS/CFT correspondence are discussed. We show that the present bound on the proton decay lifetime is inconsistent with ${\cal N} = 1$ SUSY, and strongly constrains…
We construct a minimal supersymmetric SO(10) grand unified model in 5 dimensions. The extra dimension is compactified on an S^1/(Z_2 x Z_2^\prime) orbifold which has two in-equivalent fixed points. These are flat 4-dimensional Minkowski…
In this talk we show that it is possible to find an upper bound on the total proton lifetime. We conclude that the minimal realistic non-supersymmetric grand unified theory is the modified Georgi-Glashow model with a Higgs sector composed…
We have recently proposed an alternative picture for the physics at the scale of gauge coupling unification, where the unified symmetry is realized in higher dimensions but is broken locally by a symmetry breaking defect. Gauge coupling…
The explanation of various observed phenomena such as large angle neutrino oscillations, hierarchies of charged fermion masses and CKM mixings, and apparent baryon number conservation may have a common origin. We show how this could occur…