Related papers: Unification and fermion mass relations in low stri…
We study a class of supersymmetric Froggatt-Nielsen (FN) models with multiple U(1) symmetries and Standard Model (SM) singlets inspired by heterotic string compactifications on Calabi-Yau threefolds. The string-theoretic origin imposes a…
Deriving the Yukawa couplings and the resulting fermion masses and mixing angles of the Standard Model (SM) from a more fundamental theory remains one of the central outstanding problems in theoretical high-energy physics. It has long been…
Grand gauge-Higgs unification of five dimensional SU(6) gauge theory on an orbifold $S^1/Z_2$ with localized gauge kinetic terms is discussed. The Standard model (SM) fermions on the boundaries and some massive bulk fermions coupling to the…
Recently a class of Type IIA orientifold models was constructed yielding just the fermions of the SM at the intersections of D6-branes wrapping a 6-torus. We generalize that construction to the case of Type IIB compactified on an…
We construct and analyze an $SU(6)\times SU(2)$ GUT. The model is k=1 string embedable in the sense that we employ only chiral representations allowed at the k=1 level of the associated Ka\v{c}-Moody Algebra. Both cases $SU(6)\times…
We construct a 6D supergravity theory which emerges as intermediate step in the compactification of the heterotic string to the supersymmetric standard model in four dimensions. The theory has N=2 supersymmetry and a gravitational sector…
We present analytic expressions for the top and bottom Yukawa couplings in the context of the minimal supersymmetric standard model when both couplings $h_{t,0},h_{b,0}$ are large at the unification scale. For sufficiently large…
It is known that the recently reported shift of the W boson mass can be easily explained by an $SU(2)_L$ triplet Higgs boson with a zero hypercharge if it obtains a vacuum expectation value (VEV) of $O(1)$ GeV. Surprisingly, the addition of…
In models with low-energy supersymmetry breaking, an anomalous Abelian horizontal gauge symmetry can simultaneously explain the fermion mass hierarchy and the values of the $\mu$ and $B$ terms. We construct an explicit model where the…
We review efforts in string model building, focusing on the heterotic orbifold compactifications. We survey how one can, starting from an explicit string theory, obtain models which resemble Nature. These models exhibit the standard model…
In the Standard Model of elementary particles the fermions are assumed to be intrinsically massless. Here we propose a new theoretical idea of fermion mass generation (other than by the Higgs mechanism) through the coupling with the vector…
Supersymmetry and extra dimension need not be mutually exclusive options of physics for the TeV scale and beyond. In this paper, we envisage a phenomenological scenario by embedding the 4d constrained minimal supersymmetric standard model…
We explore the implications of t-b-tau (and b-tau) Yukawa coupling unification condition on the fundamental parameter space and sparticle spectroscopy in the minimal gauge mediated supersymmetry breaking (mGMSB) model. We find that this…
We analyze all the possible continuous horizontal gauge groups G_H in relation with their possibility to explain m_b<<m_t. We assume that the only effective fermionic degrees of freedom correspond to the known fermions but allow the…
We consider composite two-Higgs doublet models based on gauge-Yukawa theories with strongly interacting fermions generating the top-bottom mass hierarchy. The model features a single "universal" Higgs-Yukawa coupling, $ g $, which is…
I discuss the properties of the minimal supersymmetric extension of the standard model, in the case in which there is a dynamical breakdown of the electroweak symmetry induced by the formation of condensates of the third generation of…
The idea of grand unification in a minimal supersymmetric SU(5)xSU(5) framework is revisited. It is shown that the unification of gauge couplings into a unique coupling constant can be achieved at a high-energy scale compatible with proton…
In the extra U(1) superstring inspired model, we examine the electroweak and U(1)-prime symmetry breaking with the singlet and exotic quark D, D+{\c}along with the study of heavy Z-prime boson in accordance with the top quark mass region.…
New vectorlike fermions that mix with the third generation can significantly affect the tau and b Yukawa couplings. Consistent with precision electroweak measurements, the width of the Higgs boson to tau tau, b b can be reduced by O(1) with…
The little hierarchy between the GUT scale and the string scale may give us some hints that can be tested at the LHC. To achieve string-scale gauge coupling unification, we introduce additional vector-like particles. We require that these…