Heavy-fermion effects ine+e−→ZHandZ→Hνν¯

We consider the effects of the one-loop radiative corrections due to virtual heavy fermions on the process $e^{+}{e}^{-}\to \mathrm{ZH}$ and on the related process $Z\to H\nu \overline{\nu }$. We show how to compute the one-loop corrections for asymptotically large fermion masses in a very simple manner, using the equivalence theorem where the on-shell $Z$ is replaced by the corresponding Goldstone scalar. Since heavy fermions do not decouple from low-energy phenomena involving the production of external Higgs bosons, the corrections lead to a significant reduction in the rate if there is a heavy fourth generation of quarks and/or leptons.