Abstract
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 SU2L scalar doublets, three inert and two active electrically neutral gauge singlet scalars, charged vector like fermions and Majorana neutrinos. These additional particles are introduced to generate the SM fermion mass hierarchy from a sequential loop suppression mechanism. In our model the top and exotic fermion masses appear at tree level, whereas the remaining fermions get their masses radiatively. Specifically, bottom, charm, tau and muon masses appear at 1-loop; the masses for the light up, down and strange quarks as well as for the electron at 2-loop and masses for the light active neutrinos at 3-loop. Our model successfully accounts for SM fermion masses and mixings and accommodates the observed Dark Matter relic density, the electron and muon anomalous magnetic moments, as well the constraints arising from charged Lepton Flavor Violating (LFV) processes. The proposed model predicts charged LFV decays within the reach of forthcoming experiments.
Highlights
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 SU2L scalar doublets, three inert and two active electrically neutral gauge singlet scalars, charged vector like fermions and Majorana neutrinos
Three of us proposed a model of fermion mass generation, where the fermion mass hierarchy arises from the sequential loop suppression, as follows [155]: t-quark → tree-level mass from Yukawa couplings, b, c, τ, μ → 1-loop mass; tree-level suppressed by a symmetry. s, u, d, e → 2-loop mass; tree-level & 1-loop suppressed by a symmetry. νi → n-loop mass (n > 2); tree-level & lower loops suppressed by a symmetry
We have constructed an extension of the 3HDM based on the Z2(1) × Z2(2) × Z4 symmetry, where the SM particle content is enlarged by two inert SU2L scalar doublets, three inert and two active electrically neutral gauge singlet scalars, charged vector like fermions and Majorana neutrinos
Summary
Before providing a complete model setup, let us explain the motivations behind introducing extra scalars, fermions and symmetries needed for a consistent implementation of the sequential loop suppression mechanism for generating the SM fermion hierarchies. The fermionic sector is enlarged by electroweak charged exotic fermions Fr, where r = 1 for quarks and r = 2 for charged leptons, and that the Yukawa operators as well as the trilinear scalar operator shown in eq (2.3) correspond to the three vertices of the one loop level diagram in the upper left panel of figure 1. Note that the SU2L singlet exotic quarks T , T, T , B, B, B and singlet leptons Es (s = 1, 2), E, E introduced in our model, correspond to the minimal amount of charged exotic fermion content needed to yield one-loop level masses for the bottom, charm quarks, tau and muon leptons, as well as two- loop level masses for the light up, down, strange quarks and the electron, without including soft-breaking mass terms. We avoid to encounter tree level Flavor Changing Neutral Currents (FCNCs)
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