Investigations of electroweak symmetry breaking mechanism for Higgs boson decays into four fermions

Models with extended Higgs boson sectors are of prime importance for investigating the mechanism of electroweak symmetry breaking for Higgs decays into four fermions and for Higgs-production in association with a vector bosons. In the framework of the Two-Higgs-Doublet Model using two scenarios obtained from the experimental measurements we presented next-to-leading-order results on the four-fermion decays of light CP-even Higgs boson, h → 4f. With the help of Monte Carlo program Prophecy 4f 3.0, we calculated the values Γ = Γ_EW / (Γ_EW + Γ_SM) and Γ = Γ_EW+QCD/ (Γ_EW+QCD + Γ_SM) for Higgs boson decay channels H ->> → ν_µµeν_e, µµee, eeee. We didn't find significant difference when accounting QCD corrections to EW processes in the decay modes of Higgs boson. Using computer programs Pythia 8.2 and FeynHiggs we calculated the following values: σ(V BH)BR(H → ZZ) and σ(V BF)BR(H → WW) for VBF production processes, σ(ggH)BR(H → WW) and σ(ggH)BR(H → ZZ) for gluon fusion production process at 13 and 14 TeV and found good agreement with experimental data. (author)