ELECTROWEAK ONE-LOOP CONTRIBUTIONS TO TOP PAIR PRODUCTION IN HADRON COLLIDERS

We give a detailed presentation of the electroweak one-loop contributi ons to the production mechanisms of top quark pairs, qqBAR --> ttBAR a nd gg --> ttBAR, for the energy range of future hadron colliders. The full gauge-invariant set of loop diagrams with Higgs, Z0 and W+/- boso ns is considered including strong Yukawa couplings. The parton cross s ections get sizeable modifications up to 40% and are sensitive to the Higgs boson mass and the Yukawa coupling. Results are also given for t he observable hadronic cross section pp --> ttXBAR, where the large co rrections at the parton level are substantially reduced to the order o f a few percent. For the electroweak Standard Model the maximum contri bution is about 7% for a light Higgs boson with M(eta) = 60 GeV. For H iggs bosons with M(eta) > 200 GeV, the electroweak contributions are t ypically (2-3)%.