Generalized screening theorem for Higgs decay processes in the two-doublet model Original Research Article

The radiative corrections to the decay processes of the neutral (CP-even) Higgs boson (H) into a longitudinal gauge boson pair, i.e. H → ZLZL and H → WL+WL− are analyzed in the two-Higgs doublet model by assuming that all of the Higgs boson masses are much greater than the W and Z bosonsʹ. These calculations are motivated to see if one could see potentially large virtual effects to these decay rates due to the charged and CP-odd neutral Higgs boson masses (mG and mA, respectively) which are supposed to be larger than mH. It is pointed out that, although the radiative corrections to the decay width Γ(H → WL+WL−) depend sensitively in general on mG and mA, there occurs a screening effect, i.e. cancellation in leading terms once we set mG = mA, so that the radiative corrections tend to be minimized. It is also pointed out that the decay rate Γ(H → ZLZL) is fairly insensitive to the other heavier Higgs masses and is possibly a good measuring tool of the Higgs mixing angle. The mechanism of these screening phenomena in the Higgs decays is explained on the basis of a new screening theorem, which we postulate with reference to the custodial symmetry in the Higgs potential.