Related papers: Flavour Democracy in Strong Unification
A grand unified $SU(5)$ theory is constructed with a hierarchical breaking of a $U(2)$ flavor symmetry. The small parameters of the squark and slepton mass matrices, necessary to solve the supersymmetric flavor-changing problem, and the…
We analyze the general structure of the fermion mass matrices in effective superstrings. They are generically given at low energy by non-trivial functions of the gauge singlet moduli fields. Interesting structures appear in particular if…
In the context of the Grand Unified MSSM, we investigate the fermion mass matrices at GUT scale. We note that from the experimental mass pattern the determinants of the Yukawa matrices at this scale can be unified with good precision.…
We suggest a simple grand unified theory where the fifth dimensional coordinate is compactified on an $S_1/(Z_2 \times Z_2')$ orbifold. This model is based on the supersymmetric flipped $SU(5) \times U(1)$ grand unified theory, which can…
The flavour puzzle is an open problem both in the Standard Model and in its possible supersymmetric or grand unified extensions. In this thesis, we discuss possible explanations of the origin of fermion mass hierarchies and mixings by the…
The models with the gauge group $SU(3)_c\times SU(3)_L \times U(1)_X$ (331-models) have been advocated to explain why there are three fermion generations in Nature. As such they can provide partial understanding of the flavour sector. The…
We present a supersymmetric SO(10) grand unified theory (GUT) of flavor based on an $S_4$ family symmetry. It makes use of our recent proposal to use SO(10) with type II seesaw mechanism for neutrino masses combined with a simple ansatz…
Lepton flavour violation has been proposed as a significant test of supersymmetric unification. Here we show that such signals are also a generic feature of supersymmetric string unified models in which there is no simple unified gauge…
Motivated by the possibility that new (gauge) symmetries which are broken at the grand- (string-) unification scale give rise to texture zeros in the fermion mass matrices which are at the origin of the hierarchy of masses and mixings we…
An unified flavour model based on U(2) as flavour group is described. Besides to explain the main characteristics of the fermion spectrum, the model is predictive and agrees quantitatively with experimental data in flavour physics.
We suggest simple models which produce the suitable fermion mass hierarchies and flavor mixing angles based on the 6 dimensional N=1 supersymmetric SO(10) grand unified theory compactified on a $T^2/(Z_2 \times Z_2')$ orbifold. We introduce…
We construct an extension of the Standard Model (SM) which is based on grand unification with Pati-Salam symmetry. The setup is supplemented with the idea of spontaneous flavour symmetry breaking which is mediated through flavon fields with…
We propose a model based on the $SU(5)$ grand unification with an extra $A_{4}\otimes Z_{2}\otimes Z_{2}^{\prime }\otimes Z_{2}^{\prime \prime}\otimes U\left( 1\right) _{f}$ flavor symmetry, which accounts for the pattern of the SM fermion…
A bottom-up approach has been adopted to identify a flavour model that agrees with present experimental measurements. The charged fermion mass hierarchies suggest that only the top Yukawa term should be present at the renormalisable level.…
We analyse the structure of Yukawa couplings in local SU(5) F-theory models with $E_7$ enhancement. These models are the minimal setting in which the whole flavour structure for the MSSM charged fermions is encoded in a small region of the…
New mechanism of generating flavor mass spectrum is proposed by using an O'Raifeartaigh-type supersymmetry breaking model. A desired bilinear form of fermion mass spectrum is naturally realized through F-components of gauge-singlet (nonet…
We examine the flavor structure of the trilinear superpotential couplings which can result from embedding the Standard Model within D brane sectors in Type IIB orientifold models, which are examples within the Type I string framework. We…
We propose a simple $U(2)$ model of flavor compatible with an $SU(5)$ GUT structure. All hierarchies in fermion masses and mixings arise from powers of two small parameters that control the $U(2)$ breaking. In contrast to previous $U(2)$…
In the four-dimensional effective theory from string compactification discrete flavor symmetries arise from symmetric structure of the compactified space and generally contain both the $R$ symmetry and non-$R$ symmetry. We point out that a…
We present a class of models based on a gauged $U(1)_F$ flavor symmetry that explains the hierarchical structure of fermion masses and mixings via the Froggatt-Nielsen (FN) mechanism, while also solving the strong CP problem by the…