RADIATIVE-CORRECTIONS TO ZZ-]ZZ IN THE ELECTROWEAK STANDARD MODEL

The cross section for ZZ --> ZZ with arbitrarily polarized Z bosons is calculated within the electroweak standard model including the comple te O(alpha) corrections. We show the numerical importance of the radia tive corrections and elaborate its characteristic features. The treatm ent of the Higgs-boson resonance is discussed in different schemes inc luding the S-matrix-motivated pole scheme and the background-field met hod. The numerical accuracy of the equivalence theorem is investigated by comparing the cross sections for purely longitudinal Z bosons obta ined from the equivalence theorem and from the complete calculation. I n this context the full O(alpha) corrections are also confronted with the enhanced corrections of O(alpha M-H(2)/s(w)(2)M(w)(2)), which were frequently used in the literature.