2HDMにおけるILCでのヒッグス粒子対生成過程

Abstract

We study the Higgs boson pair production e^+ e^- → ff^^-hh (f ≠ t) in the two-Higgs-doublet model with the softly-broken Z_2 symmetry with the CP-invariance. In the case without the alignment limit, the cross section can be significantly enhanced, i.e., a few hundred percent levels as compared to that in the standard model, due to resonant effects of heavy neutral Higgs bosons. We find the correlation between the enhancement factor of the cross section and the scaling factor of the ff^^-h couplings (k_f) under constraints from the perturbative unitarity, the vacuum stability and the current experimental data at the LHC as well as the electroweak precision data.