Precise Predictions for Higgs Production at e+e- Colliders and Numerical Calculation of One-Loop Integrals

Some of the most interesting Higgs-production processes at future e+e- colliders are of the type e+e- → ff(bar)H. We present a calculation of the complete O(α) corrections to these processes in the Standard Model for final-state neutrinos and top quarks. Initial-state radiation beyond O(α) at the leading-logarithmic level as well as QCD corrections are also included. The electroweak corrections turn out to be sizable and reach the order of ±10% and will thus be an important part of precise theoretical predictions for future e+e- colliders. Furthermore, an overview is given of a technique for a fast and reliable numerical calculation of multi-leg one-loop integrals. The method is numerically stable also for exceptional momentum configurations and easily allows the introduction of complex masses and the calculation of higher orders in the expansion around D = 4. (author)