Related papers: Composite fermions in Electroweak Symmetry Breakin…
We study flavor violation in a supersymmetric SU(5) grand unification scenario in a model-independent way employing mass insertions. We examine how the quark and the lepton sector observables restrict sfermion mixings. With a low soft…
A suitably broken U(2)^3 symmetry acting on the first two generations of quarks and squarks is studied as a natural generalization of the Minimal Flavour Violation principle to the case of a hierarchical squark spectrum. A definite…
The updated analysis of the LHCb Collaboration on the lepton flavor violation suggests that the new physics should couple to muons and electrons with comparable magnitudes, resulting in the anomalies in both rare decay channels, $b…
Flavor democracy broken in the fermion mass matrix by means of small perturbations can give rise to hierarchical fermion masses. We study the breaking of the $S^L_3 \times S^R_3$ symmetry associated with democratic mass matrices to a…
We discuss the possibility of breaking the electroweak symmetry in theories with extra dimensions via boundary conditions, without a physical Higgs scalar in the spectrum. In these models the unitarity violation scale can be delayed via the…
We analyse the recent hints of Lepton Flavor Universality violations in semi-leptonic $B$ decays within a general EFT based on a $U(2)^n$ flavor symmetry acting on the light generations of SM fermions. We analyse in particular the…
We argue that the A_4 symmetry as required by three flavors of fermions may well-embed in the SU(3)_C X SU(3)_L X U(1)_X gauge model. The new neutral fermion singlets as introduced in a canonical seesaw mechanism can be combined with the…
New heavy particles in an SU(2)_L multiplet, sometimes introduced in extensions of the standard model, have highly degenerate tree-level mass M if their couplings to the Higgs bosons are very small or forbidden. However, loop corrections…
A new approach to EW composite scalars is developed, starting from the fundamental gauge interaction on high scale. The latter is assumed to have the group structure $SU(2)_L \times SU(2)_R\times SU(4)$ where SU(4) is the Pati-Salam…
This note presents an analysis of lepton-flavour-violating muon decays within the framework of a low-energy effective field theory that contains higher-dimensional operators allowed by QED and QCD symmetries. The decay modes $\mu\to e…
We discuss extensions of the Standard Model through extending the electroweak gauge symmetry. An extended electroweak symmetry requires a list of extra fermionic and scalar states. The former is necessary to maintain cancellation of gauge…
Evidences of a discrete symmetry behind the pattern of lepton mixing are analyzed. The program of "symmetry building" is outlined. Generic features and problems of realization of this program in consistent gauge models are formulated. The…
Starting from a chiral invariant and quark line rule conserving Lagrangian of pseudoscalar and vector nonets we introduce first and second order symmetry breaking as well as quark line rule violating terms and fit the parameters, at tree…
The non-unitarity of the effective leptonic mixing matrix at low energies is a generic signal of extensions of the Standard Model (SM) with extra fermionic singlet particles, i.e. sterile or right-handed neutrinos, to account for the…
In a simple extension of the standard model (SM), a pair of vector like lepton doublets ($L_1$ and $L_2$) and a $SU(2)_L$ scalar doublet ($\eta$) have been introduced to help in accommodating the discrepancy in determination of the…
We review recent work on realistic models that break supersymmetry dynamically and give rise to composite quarks and leptons, all in a single sector. These models have a completely natural suppression of flavor-changing neutral currents,…
We study the implications of a large nu_mu - nu_tau mixing angle on flavour changing transitions of quarks and leptons in supersymmetric extensions of the standard model. Two patterns of supersymmetry breaking are considered, models with…
We explore the scenario in which the breaking of the electroweak symmetry is due to the simultaneous presence and interplay of a dynamical sector and an unnatural elementary Higgs. We introduce a low energy effective Lagrangian and…
We complete the analysis of the effective field theory at the electroweak scale for minimal models of fundamental partial compositeness. Specifically, we consider fermions in the complex and real representation of the gauge group underlying…
Beyond Standard Model physics frequently connects flavor symmetry with a discrete group. If the discrete symmetry arises spontaneously from a gauge theory, one can maintain compatibility with quantum gravity and avoid anomalies. We provide…