Related papers: Yukawa structure, flavour and CP violation in Supe…
Strong gauge and top-Yukawa couplings predicted in the presence of extra dimensions lead to a trickle-down effect of the top-coupling through the renormalization group equations for the quark Yukawa matrices. The matrix elements for the u…
The condition of unification of gauge couplings in the minimal supersymmetric standard model provides successful predictions for the weak mixing angle as a function of the strong gauge coupling and the supersymmetric threshold scale. In…
As a minimal theory of fermion masses we extend the SM by heavy vectorlike fermions, with flavor-anarchical Yukawa couplings, that mix with chiral fermions such that small SM Yukawa couplings arise from small mixing angles. This model can…
A simple breaking of the subnuclear democracy of the quarks leads to a mixing between the secons and the third family, in agreement with observation. Introducing the mixing between the first and the second family, one finds an interesting…
It is pointed out that in a seesaw quark mass matrix model which yields a singular enhancement of the top-quark mass, the right-handed fermion-mixing matrix U_R^u for the up-quark sector has a peculiar structure in contrast to the…
We explore the low energy phenomenology of an F-theory based SU(5) model which, in addition to the known quarks and leptons, contains Standard Model singlets, and vector-like color triplets and SU(2) doublets. Depending on their masses and…
Functional Renormalisation Group (FRG) equations are constructed for a simple Yukawa-model with discrete chiral symmetry, including also the effect of a nonzero composite fermion background beyond the conventional scalar condensate. The…
We investigate the possibility of satisfying the $SU(5)$ boundary condition $\mathbf{Y}^d=\mathbf{Y}^{e\,T}$ at the GUT scale within the renormalizable $R$-parity conserving Minimal Supersymmetric Standard Model (MSSM). Working in the…
The fermion spectrum in the Standard Model (SM) exhibits hierarchical structures between the eigenvalues of the Yukawa matrices which determine the fermion masses, as well as certain hierarchical patterns in the mixing matrix that describes…
We analyze fermion masses and mixing in a general warped extra dimensional model, where all the Standard Model (SM) fields, including the Higgs, are allowed to propagate in the bulk. In this context, a slightly broken flavor symmetry…
It has been recently claimed that the symmetry group S4 yields to the Tri-bimaximal neutrino mixing in a "natural" way from the group theory point of view. Approving of this feature as an indication, we build a supersymmetric model of…
We propose a supersymmetric SU(5)xSU(5) model, where the quarks and leptons live in a U(1) product group theory space that is compactified on the real projective plane RP^2. The fermion generations are placed on different points in the…
Strongly coupled supersymmetric theories can give rise to composite quarks and leptons at low energy. We show that the internal structure of these particles can explain the origin of three generations and provide a qualitative understanding…
We present empirical relations that connect the dimensionless ratios of fermion masses for the charged lepton, up-type quark and down-type quark sectors. Explaining these relations from first principles imposes strong constraints on the…
The first fermion family might play a special role in understanding the physics of flavour. This possibility is suggested by the observation that the up-down splitting within quark families increases with the family number: $ m_u\sim m_d$,…
We explore calculable models with low-energy supersymmetry where the flavor hierarchy is generated by quark and lepton compositeness, and where the composites emerge from the same sector that dynamically breaks supersymmetry. The observed…
Hypotheses of the universal seesaw mechanism and the {\it universal strength for Yukawa couplings} are applied to explain one possible origin of quasi-democratic mass matrices of a special type in a left-right symmetric model with the gauge…
We investigate the impact on low energy flavour mixing phenomena of the renormalisation group running of parameters in supersymmetric theories. We have explicitly chosen flavour dependent supergravity couplings. The renormalisation group…
We use the natural $SU(3)\times U(1)$ global symmetry of the gauge-fermion interaction sector of the standard model to discuss the fermion mass hierarchy problem. The $SU(3)$ sixtet and triplet Higgs are introduced. The Yukawa sector is…
In a model with a gauge group $G_{SM}\otimes U(1)_X$, where $G_{SM} \equiv SU(3)_C \otimes SU(2)_L \otimes U(1)_Y$ is the standard model gauge group and $U(1)_X$ is a horizontal local gauge symmetry, the spectrum of charged fermion masses…