Abstract
The models based on SU(3)C × SU(3)L × U(1)X gauge symmetry (331-models) have been advocated to explain the number of fermion families. These models place one quark family to a different representation than the other two. The traditional 331-models are plagued by scalar mediated quark flavour changing neutral currents (FCNC) at tree- level. So far there has been no concrete mechanisms to suppress these FCNCs in 331- models. Recently it has been shown that the Froggatt-Nielsen mechanism can be incorporated into the 331-setting in an economical fashion (FN331-model). The FN331-model explains both the number of fermion families in nature and their mass hierarchy simultaneously. In this work we study the Higgs mediated quark FCNCs in FN331-model. The flavour violating couplings of quarks are suppressed by the ratio of the SU(2)L × U(1)Y and SU(3)L × U(1)X breaking scales. We find that the SU(3)L × U(1)X -breaking scale can be as low as 5 TeV in order to pass the flavour bounds.
Highlights
The Standard Model of particle physics (SM) [1]–[3] has been enormously successful in explaining experimental results
We find the flavour changing neutral currents (FCNC) to be naturally suppressed in FN331-model
The Froggatt-Nielsen mechanism serves a purpose, other than that of generating the fermion mass hierarchy: the scalar mediated flavour changing neutral currents are in part suppressed due to the FN-mechanism
Summary
The Standard Model of particle physics (SM) [1]–[3] has been enormously successful in explaining experimental results. The FN331-model uses the existing scalar content of a 331-model to emulate the flavon in the Froggatt-Nielsen mechanism, in contrast to the FN mechanism in SM where the scalar sector has to be extended This is interesting since the 331-models can explain the number of fermion families. The scalar sector in those models is quite complicated, since the generation of masses to all of the charged fermions at tree-level requires three scalar triplets and one scalar sextet These models contain particles with exotic electric charges, such as doubly charged bosons and quarks with electric charges ±5/3 and ±4/3. The FN331-model employs the FN mechanism for the generation of the Yukawa couplings and the form of the fermion diagonalization matrices is known This allows us to study the flavour violating Yukawa couplings of quarks in great detail.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
