Related papers: Treating Top Differently from Charm and Up
In order to explain the fermions masses and mixing parameters appearing in the lepton sector of the Standard Model, one proposes the extension of its symmetry. A discrete, non-abelian subgroup of $U(3)$ is added to the gauge group…
Precision measurements of the Higgs couplings are, for the first time, directly probing the mechanism of fermion mass generation. The purpose of this work is to determine to what extent these measurements can distinguish between the…
In the Standard Model, Yukawa couplings parametrize the fermion masses and mixing angles with the exception of neutrino masses. The hierarchies and apparent regularities among the quark and lepton masses are, however, otherwise a mystery.…
The origin of mass must lie in physics beyond the Standard Model. Dynamical electroweak symmetry breaking models like technicolor can generate masses for the W and Z bosons. Providing the large top quark mass and large top-bottom mass…
I present a new model for the quark mass matrices, which uses four scalar doublets together with a horizontal symmetry S3 x Z3. The model is inspired on a suggestion made a few years ago by Ma, but it is different. The predictions |Vts|…
We consider finite groups of small order for family symmetry. It is found that the binary dihedral group Q_6, along with the assumption that the Higgs sector is of type II, predicts mass matrix of a nearest neighbor interaction type for…
We study the flavor physics in two extensions of the quark sector of the Standard Model (SM): a four generation model and a model with a single vector--like down--type quark (VDQ). In our analysis we take into account the experimental…
We propose an extension of the three-Higgs-doublet model (3HDM), where the Standard Model (SM) particle content is enlarged by the inclusion of two inert $SU_{2L}$ scalar doublets, three inert and two active electrically neutral gauge…
Present data on neutrino masses and mixing favor the highly symmetric tribimaximal neutrino mixing matrix which suggests an underlying flavor symmetry. A systematic study of non-abelian finite groups of order $g \leq 31$ reveals that…
We propose a Three Higgs Doublet Model (3HDM) that goes beyond natural flavor conservation and in which each of the three Higgs doublets couples mainly to a single generation of fermions via non-standard Yukawa structures. A hierarchy in…
We study a toy ${\rm SU}(6)$ model with the symmetry breaking pattern of the extended $331$ symmetry of ${\rm SU}(3)_c \otimes {\rm SU}(3)_W \otimes {\rm U}(1)_X$. A "fermion-Higgs mismatching" symmetry breaking pattern is proposed for more…
We examine the structure of the quaternion group $Q_8$ and its possible application to the physics of flavor. We find that a $Q_8$ family symmetry is suitable to explain the difference between quark and lepton mixing patterns. Distinctive…
We propose a Randall-Sundrum model with a bulk family symmetry based on the double tetrahedral group, T', which generates the tri-bimaximal neutrino mixing pattern and a realistic CKM matrix, including CP violation. Unlike 4D models where…
One of the most important and unanswered problems in particle physics is the origin of the three generations of quarks and leptons. The standard Model does not provide any hint regarding its sequential charge assignments, which remain a…
We review scenarios of physics beyond the Standard Model in which the top quark plays a special role. Models that aim at the stabilization of the weak scale are presented together with the specific phenomenology of partner states that are…
We use the permutational symmetry group $S_{3}$ as a symmetry of flavour, which leads to a unified treatment of masses and mixings of the quarks and leptons. In this framework all mass matrices of the fermions in the theory have the same…
We introduce a simple flavor symmetry breaking scheme, in which charged lepton masses have a strong hierarchy and neutrino masses are almost degenerate. It is possible to obtain a natural suppression of lepton flavor mixing between the 1st…
In the framework of a complete vector-like and universal gauged SU(3)_F family symmetry, we report a global region in the parameter space where this approach can account for a realistic spectrum of quark masses and mixing in a 4 x 4…
The heaviness of the third family fermions and the experimental absence of large flavor violating processes suggest, in supersymmetric theories, that the three families belong to a $2+1$ representation of a horizontal symmetry $G_H$. In…
Based on experimental mass hierarchy, a set of flavor-democratic (FD) quark mass matrices at low energies is discussed. The model predicts CP violation parameters $J_{CP}=(0.3 \pm 0.2) 10^{-4}$ and ${\epsilon'/\epsilon} = (0.6 \pm 0.5)…