Enhancement of the loop-induced H+/-W+/-Z0 vertex in the two-Higgs-doublet model -: art. no. 095001

The nondecoupling effects of heavy Higgs bosons as well as fermions on the loop-induced H(+)W(+)Z(o) vertex are discussed in the general two-Higgs-doublet model. The decay width of the process H+ --> W+ Z(o) is calculated at the one-loop level and the possibility of its enhancement is explored. We find that the novel enhancement of the decay width can occur by Higgs nondecoupling effects with large mass splitting between the charged Higgs boson and the CP-odd one. This is due to the large breakdown of the custodial SU(2)(v) invariance in the Higgs sector. Such a situation is possible even if we take into account the experimental constraint on the rho parameter. The branching ratio can amount to 10(-2) - 10(-1) for m(H+) = 300 GeV. Hence this mode may be detectable at the CERN LHC or future e(+)e(-) linear colliders.