Two-loop formfactors in theories with mass gap and Z-boson production

Abstract The non-factorizable two-loop corrections to the formfactor both for a U ( 1 ) × U ( 1 ) and a SU ( 2 ) × U ( 1 ) gauge theory with massive and massless gauge bosons respectively are evaluated at arbitrary momentum transfer q 2 . The asymptotic behaviour for q 2 → ∞ is compared to a recent calculation of Sudakov logarithms. The result is an important ingredient for the calculation of radiative corrections to Z -boson production at hadron and lepton colliders.