Anomalous high-energy behaviour in boson fusion

The magnitude is discussed of the off-shell correction terms to the equivalent-boson approximation used in SSC phenomenology, with emphasis on Higgs production. Although formally subleading, these terms are not small and give rise to cross sections that increase unacceptably at high invariant mass of the boson pair. This is traced to the fact that for off-shell bosons the set of diagrams which has been considered so far is not gauge-invariant. It is concluded that only a much more complete set of Feynman diagrams can yield a reliable prediction for the production of a heavy Higgs boson. (orig.)