相关论文: Generation Mass Hierarchy in Superstring Derived M…

We develop a formalism that allows a complete classification of four-dimensional Z2XZ2 heterotic string models. Three generation models in a sub-class of these compactifications are related to the existence of three twisted sectors in Z2XZ2…

The three generation superstring models in the free fermionic models have had remarkable success in describing the real--world. The most explored models use the NAHE set to obtain three generations and to separate the hidden and observable…

We discuss a toy model in six dimensions that predicts two fermion generations, natural mass hierarchy and intergenerational mixing. Matter is described by vector-like six dimensional fermions, one per each irreducible standard model…

A fourth generation of Standard Model (SM) fermions is usually considered unlikely due to constraints from direct searches, electroweak precision measurements, and perturbative unitarity. We show that fermion mass textures consistent with…

We consider a supersymmetric model that uses partial compositeness to explain the fermion mass hierarchy and predict the sfermion mass spectrum. The Higgs and third-generation matter superfields are elementary, while the first two matter…

We suggest a simple supersymmetric SO(10) grand unified theory in 6 dimensions which produces the suitable fermion mass hierarchies. The 5th and 6th dimensional coordinates are compactified on a $T^2/Z_2$ orbifold. The gauge and Higgs…

We give a model-independent discussion of fermion masses in four-dimensional heterotic superstring theories. We discuss the tree level contributions and quantum corrections, including one-loop threshold effects and masses generated as a…

The observed hierarchical charged fermion masses of three generations seem to imply that these masses are originally universal for three generations and then get exponential suppression with "quantized exponents" by some mechanism. We argue…

We construct a supersymmetric model based on $T'\otimes Z_3\otimes Z_9$ flavor symmetry. At the leading order, the charged lepton mass matrix is not diagonal, $T'$ is broken completely, and the hierarchy in the charged lepton masses is…

We study a possible gauge symmetry breaking pattern in an ${\rm SU}(7)$ grand unified theory, which describes the mass origins of all electrically charged SM fermions of the second and the third generations. Two intermediate gauge…

Fermion mass models usually contain a horizontal symmetry and therefore fail to predict the exponential mass spectrum of the Standard Model in a natural way. In dynamical symmetry breaking there are different concepts to introduce a fermion…

We investigate orbifold compactifications of the heterotic string, addressing in detail their construction, classification and phenomenological potential. We present a strategy to search for models resembling the minimal supersymmetric…

In non-supersymmetric grand unified models a ``radiative fermion mass hierarchy" can be achieved in which the spectrum of quark and lepton masses is determined entirely by physics at the unification scale, with many relations following from…

We present a new mechanism for solving the fermionic masses and mixing hierarchies of the standard model through a minimal symmetry $\mathcal{Z}_2 \times \mathcal{Z}_5$. The mechanism is also capable of explaining the neutrino masses and…

This thesis provides a classification of the chiral content of the heterotic $\mathbbm{Z}_2 \times \mathbbm{Z}_2$ orbifold models. We show that the chiral content of the heterotic $\mathbbm{Z}_2 \times \mathbbm{Z}_2$ orbifold models at any…

We examine the problem of constructing three generation free fermionic string models with grand unified gauge groups. We attempt the construction of $G\times G$ models, where $G$ is a grand unified group realized at level 1. This structure…

The free fermionic construction of the heterotic string in four dimensions produced a large space of three generation models with the underlying $SO(10)$ embedding of the Standard Model states. The $SO(10)$ symmetry is broken to a subgroup…

We obtain three generation SU(3)_c X SU(2)_L X U(1)_Y string models in all of the exactly solvable (0,2) constructions sampled by fermionization. None of these examples, including those that are symmetric abelian orbifolds, rely on the Z_2…

We reconsider the phenomenon of mass generation via coordinate-dependent compatifications of higher-dimensional theories on orbifolds. For definiteness, we study a generic five-dimensional (5D) theory compactified on S^1/Z_2. We show that…

We show how identification of absolutely flat directions allows the construction of a new class of compactified string theories with reduced gauge symmetry that may or may not be continuously connected to the original theory. We use this…