An effective field theory approach to the electroweak corrections at LEP energies

Ln the framework of the effective field theory (EFT) we discuss the electroweak (EW) corrections at LEP energies. We obtain the effective Lagrangian in the large m(t) limit, and reproduce analytically the dominant EW corrections to the LEP2 processes e(+) e(-) --> gamma Z and e(+) e(-) --> ZZ. To include effects of finite top-quark and Higgs masses, we use the effective Lagrangian at tree level and fit LEP1/SLD observables with four arbitrary parameters, plus alpha(s)(m(Z)). The EFT approach works remarkably well. Using the effective couplings determined from the fit, and tree-level EFT formulae, we predict the cross sections for e(+) e(-) --> ZZ, gamma Z at a level better than 1%. (C) 1999 Elsevier Science B.V. All rights reserved.