Approximations for W-Pair Production at Linear-Collider Energies

We determine the accuracy of various approximations to the O(α) corrections for onshell W-pair production. While an approximation based on the universal corrections arising from initial-state radiation, from the running of α, and from corrections proportional to m2t fails in the Linear-Collider energy range, a high-energy approximation improved by the exact universal corrections is sufficiently good above about 500GeV. These results indicate that in Monte Carlo event generators for off-shell W-pair production the incorporation of the universal corrections is not sufficient and more corrections should be included. CERN-TH/97-128 June 1997 Contribution to the Proceedings of the Joint ECFA/DESY Study: Physics and Detectors for a Linear Collider, Frascati, London, Munich, Hamburg, February 5 to November 22, 1996. Approximations for W-Pair Production at Linear-Collider Energies A. Denner and S. Dittmaier 1 PSI, Würenlingen und Villigen, Switzerland 2 CERN, Theory Division, Geneva, Switzerland