  We comprehensively evaluate renormalized Higgs boson couplings at one-loop
level in non-minimal Higgs models such as the Higgs Singlet Model (HSM) and the
four types of Two Higgs Doublet Models (THDMs) with a softly-broken $Z_2$
symmetry. The renormalization calculation is performed in the on-shell scheme
improved by using the pinch technique to eliminate the gauge dependence in the
renormalized couplings. We first review the pinch technique for scalar boson
two-point functions in the Standard Model (SM), the HSM and the THDMs. We then
discuss the difference in the results of the renormalized Higgs boson couplings
between the improved on-shell scheme and the ordinal one with a gauge
dependence appearing in mixing parameters of scalar bosons. Finally, we widely
investigate how we can identify the HSM and the THDMs focusing on the pattern
of deviations in the renormalized Higgs boson couplings from predictions in the
SM.
