By means of a low-energy theorem, we analyze at $O\left({\alpha }_s{G}_F{M}_Q^2\right)$ the shifts in the standard-model $W^{+}{W}^{-}H$ and $\mathrm{ZZH}$ couplings induced by virtual high-mass quarks $Q$ with $M_Q\gg M_Z, M_H$, which includes the top quark. Invoking the improved Born approximation, we then find the corresponding corrections to various four- and five-point Higgs-boson production and decay processes which involve the $W^{+}{W}^{-}H$ and $\mathrm{ZZH}$ vertices with one or both of the gauge bosons being connected to light-fermion currents, respectively. This includes $e^{+}{e}^{-}\to f\overline{f}H$ via Higgs radiation, via $W^{+}{W}^{-}$ fusion (with $f={\nu }_e$), and via $\mathrm{ZZ}$ fusion (with $f=e$), as well as $H\to 2V\to 4f$ (with $V=W, Z$).

• Received 30 August 1995

DOI:https://doi.org/10.1103/PhysRevD.53.6477