Advanced search    

Search: authors:"G. C. Branco"

6 papers found.
Use AND, OR, NOT, +word, -word, "long phrase", (parentheses) to fine-tune your search.

Vector-like quarks at the origin of light quark masses and mixing

We show how a novel fine-tuning problem present in the Standard Model can be solved through the introduction of a \(Z_6\) flavour symmetry, together with three \(Q = - 1/3\) quarks, three \(Q = 2/3\) quarks, as well as a complex singlet scalar. The \(Z_6\) symmetry is extended to the additional fields and it is an exact symmetry of the Lagrangian, only softly broken in the scalar ...

Group-theoretic restrictions on generation of CP-violation in multi-Higgs-doublet models

It has been known since decades that imposing a symmetry group G on the scalar sector of multi-Higgs-doublet models has consequences for CP -violation. In all examples of two- and three-Higgs-doublet models equipped with symmetries, one observes the following intriguing property: if G prevents explicit CP -violation (CPV), at least in the neutral Higgs sector, then it also prevents ...

Flavour-changing Higgs couplings in a class of two Higgs doublet models

We analyse various flavour-changing processes like \(t\rightarrow hu,hc\), \(h\rightarrow \tau e,\tau \mu \) as well as hadronic decays \(h\rightarrow bs,bd\), in the framework of a class of two Higgs doublet models where there are flavour-changing neutral scalar currents at tree level. These models have the remarkable feature of having these flavour-violating couplings entirely ...

Natural quasi-alignment with two Higgs doublets and RGE stability

In the context of two Higgs doublet models, we study the conditions required in order to have stable quasi-alignment in flavour space. We show that stability under the renormalisation group equations imposes strong constraints on the flavour structure of the Yukawa couplings associated to each one of the Higgs doublets. In particular, we find a novel solution, where all Yukawa ...

Physical constraints on a class of two-Higgs doublet models with FCNC at tree level

We analyse the constraints and some of the phenomenological implications of a class of two Higgs doublet models where there are flavour-changing neutral currents (FCNC) at tree level but the potentially dangerous FCNC couplings are suppressed by small entries of the CKM matrix V. This class of models have the remarkable feature that, as a result of a discrete symmetry of the ...

Flavor physics of leptons and dipole moments

This chapter of the report of the “Flavor in the era of the LHC” Workshop discusses the theoretical, phenomenological and experimental issues related to flavor phenomena in the charged lepton sector and in flavor conserving CP-violating processes. We review the current experimental limits and the main theoretical models for the flavor structure of fundamental particles. We analyze ...