Related papers: GUTs and Exceptional Branes in F-theory - II: Expe…
I review the theoretical expectactions for the top-quark mass in a variety of models: the Standard Model, unified models (GUTs), low-energy supersymmetric models (SUSY), unified supersymmetric models (SUSY GUTs), supergravity models, and…
Many of the ingredients are explored which are needed to develop a super- symmetric SO(10) x U(1)_F grand unified model based on the Yukawa structure of a model previously constructed in collaboration with S. Nandi to explain the quark and…
The gauge principle is a cornerstone of particle-physics model building. Nevertheless, many constructions leave certain global $U(1)$ redundancies ungauged. In this work, we take the gauge principle to its logical extreme by promoting all…
Recently, extra dimensional SUSY GUT models have been proposed in which compactification of the extra dimension(s) leads to a breakdown of the gauge symmetry and/or supersymmetry. We examine a particular class of higher-dimensional models…
We present a simple scheme for constructing models that achieve successful gauge mediation of supersymmetry breaking. In addition to our previous work [1] that proposed drastically simplified models using metastable vacua of supersymmetry…
We discuss the fermion mass problem in SUSY GUTs, including such ideas as texture zeroes, and Georgi-Jarlskog textures. We focus on a specific supersymmetric model based on the gauge group $SU(4)\otimes SU(2)_L \otimes SU(2)_R$. In this…
Recently we proposed a natural scenario of grand unified theories with anomalous U(1)_A gauge symmetry, in which doublet-triplet splitting is realized in SO(10) unification using Dimopoulos-Wilczek mechanism and realistic quark and lepton…
F-theory is a non-perturbative formulation of type IIB superstring theory which allows for the decoupling of gravity and for the formulation of GUT theories based on the gauge group E6. In this paper we explore F-theory models in which the…
The basic tools for model building in F-theory are reviewed and applied to the construction of SU(5) models. The flux mechanism for gauge symmetry breaking and doublet triplet splitting is analysed. A short account for the gauge coupling…
The pseudo-Goldstone boson mechanism for the ``doublet-triplet splitting'' problem of the grand unified theory can be naturally implemented in the scenario with extra dimensions and branes. The two SU(6) global symmetries of the Higgs…
We discuss the construction of four dimensional non-supersymmetric models obtained from configurations of D6-branes intersecting at angles. We present the first examples of string GUT models which break exactly to the Standard Model (SM) at…
We study a softly-broken supersymmetric model whose gauge symmetry is that of the standard model (SM) gauge group times an extra Abelian symmetry U(1)'. We call this gauge-extended model U(1)' model, and we study a U(1)' model with a…
We propose a supersymmetric hypercolor SU(3)_H gauge theory interacting strongly at the grand unification scale, in which the hyperquark condensation breaks SU(5)_GUT down to SU(3)_C x SU(2)_L without unbroken U(1)_Y at the classical level.…
D3-brane probes of exceptional Yukawa points in F-theory GUTs are natural hidden sectors for particle phenomenology. We find that coupling the probe to the MSSM yields a new class of N = 1 conformal fixed points with computable infrared…
We study the low-scale predictions of the supersymmetric model extended by $U(1)_R \times U(1)_{B-L}$ symmetry, obtained by breaking $SO(10)$ symmetry at GUT scale via a left-right supersymmetric model. Two new singlet Higgs fields…
We propose an adjoint $SU(5)$ GUT model with a $T_{7}$ family symmetry and an extra $Z_{2}\otimes Z_{3}\otimes Z_{4}\otimes Z_{4}^{\prime }\otimes Z_{12}$ discrete group, that successfully describes the prevailing Standard Model fermion…
Grand Unified Theories (GUTs) usually predict wrong Standard Model (SM) fermion mass relation m_e/m_{\mu} = m_d/m_s toward low energies. To solve this problem, we consider the Generalized Minimal Supergravity (GmSUGRA) models, which are…
Grand Unified Theories (GUTs) are a very well motivated extensions of the Standard Model (SM), but the landscape of models and possibilities is overwhelming, and different patterns can lead to rather distinct phenomenologies. In this work…
We study unification in the Randall-Sundrum scenario for solving the hierarchy problem, with gauge fields and fermions in the bulk. We calculate the one-loop corrected low-energy effective gauge couplings in a unified theory, broken at the…
The recent excess in diphoton events around 750 GeV seen by the ATLAS and CMS experiments could be hinting at the existence of new vector-like charged matter around the TeV scale which couples to a singlet. Such a spectrum of exotics arises…