Flavor violating Higgs signals, such as the top FCNC decay t → ch 0 and the LFV Higgs decay h 0 → τ µ, have been studied at the LHC. These signals can arise within the general Two-Higgs doublet model (THDM), where each Higgs doublet couples to all fermions types through Yukawa matrices Y f 1 and Y f 2 . The Yukawa matrices can be assumed to have the same form or they could have different structures. In this paper we study the case when both Y f 1 and Y f 2 have completely different forms, but in such a way that they complement to produce a specific hermitian mass matrix. We find that for specific four-zero textures, the Flavor Violating Higgs couplings depend only on the free parameters tan β, γ f and the fermion masses. We use the current bounds on the low energy processes, to derive constraints on the Heavy Higgs boson mass, tan β and γ f . Then, we use these constraints to evaluate the LFV Higgs decays, which reach Branching ratios that could be tested at the LHC.
The search for flavons with a mass of Oð1Þ TeV at current and future colliders might probe low-scale flavor models. We are interested in the simplest model that invokes the Froggatt-Nielsen mechanism with an Abelian flavor symmetry, which includes a Higgs doublet and a Froggatt-Nielsen complex singlet. Assuming a CP conserving scalar potential, there are a CP-even H F and a CP-odd A F flavons with lepton flavor violating (LFV) couplings. The former can mix with the standard-model-like Higgs boson, thereby inducing tree-level LFV Higgs interactions that may be at the reach of the LHC. We study the constraints on the parameter space of the model from low-energy LFV processes, which are then used to evaluate the flavon decay widths and the gg → ϕ → τμ (ϕ ¼ H F ; A F ) production cross section at hadron colliders. After imposing several kinematic cuts to reduce the standard model main background, we find that for m H F about 200-350 GeV, the decay H F → τμ might be at the reach of the LHC for a luminosity in the range 1-3 ab −1 , however, a luminosity of the order of 10 ab −1 would be required to detect the A F → τμ decay. On the other hand, a future 100 TeV pp collider could probe masses as high as Oð10Þ TeV if it reaches an integrated luminosity of at least 20 ab −1 . Therefore, the 100 TeV Collider could work as a flavon factory.
We study the magnetic and weak magnetic dipole moments of charged leptons in the framework of the Two Higgs Doublet Model type III (THDM-III) with four zero textures. We first analyze the possibility that the discrepancy between the experimental measurements and the theoretical prediction of the muon anomalous magnetic dipole moment (aµ) in the Standard Model (SM) can be explained in the context of the model and then find values for the parameters of the THDM-III: neutral and charged Higgs boson masses (mH , m H ± ), mixing angles (α, β), CP-violating angles θ1, θ2 and an additional parameter arising from the mass matrix (γ f ), for which a correspondence between theory and experiment is possible. We use a T HDM −III µ and current low energy processes K −K mixing, B 0 s → µμ, τ → µµμ, µ → eeē, τ → µγ, τ → eγ, µ → eγ, b → sγ, B → D(D * )τ ν and the rare higgs decay h → τ µ in order to determine the allowed parameter space of THDM-III and from these we give a prediction for the magnetic and weak magnetic dipole moment of charged leptons, in particular of the τ lepton. The obtained magnetic dipole moment of the τ lepton is of the order of O(10 −8 − 10 −7 ) and the weak magnetic is of the order O(10 −10 − 10 −7 ).
We obtain analytical expressions, both in terms of parametric integrals and Passarino-Veltman scalar functions, for the one-loop contributions to the anomalous weak magnetic dipole moment (AWMDM) of a charged lepton in the framework of the simplest little Higgs model (SLHM). Our results are general and can be useful to compute the weak properties of a charged lepton in other extensions of the standard model (SM). As a by-product we obtain generic contributions to the anomalous magnetic dipole moment (AMDM), which agree with previous results. We then study numerically the potential contributions from this model to the τ lepton AMDM and AWMDM for values of the parameter space consistent with current experimental data. It is found that they depend mainly on the energy scale f at which the global symmetry is broken and the t β parameter, whereas there is little sensitivity to a mild change in the values of other parameters of the model. While the τ AMDM is of the order of 10 −9 , the real (imaginary) part of its AWMDM is of the order of 10 −9 (10 −10 ). These values seem to be out of the reach of the expected experimental sensitivity of future experiments.
We calculate the ratios Rτ/P≡ Γ (τ → Pντ [γ]) /Γ (P → μνμ [γ]) (P = π, K) at one loop following a large-NC expansion where Chiral Perturbation Theory is enlarged by including the lightest resonances and respecting the short-distance behavior dictated by QCD. We find δRτ/π = (0.18 ± 0.57)% and δRτ/K = (0.97 ± 0.58)%, where the uncertainties are induced fundamentally by the counterterms. We test the lepton universality, obtaining |gτ/gμ|π = 0.9964 ± 0.0038 and |gτ/gμ|K = 0.9857 ± 0.0078, and analyze the CKM unitarity, getting results at 2.1σ and 1.5σ from unitarity via |Vus/Vud| and |Vus|, respectively. We also update the search for non-standard interactions in τ decays. As a by-product, we report the theoretical radiative corrections to the τ → Pντ [γ] decay rates: δτπ = −(0.24 ± 0.56)% and δτK = −(0.15 ± 0.57)%.
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