  The physics of high-energy collider experiments asks for delicate comparisons
between theoretical predictions and experimental data. Signals and potential
backgrounds for new physics have to be predicted at sufficient accuracy. The
accuracy as well as the computational complexity of the calculations leading to
the predictions depend on both the number of external particles in the process
analyzed and the order of the quantum corrections, the number of loops,
included in the calculation. We present some approaches to problems occurring
in these calculations regarding the integration of phase-space and the
inclusion of one-loop corrections.

High Energy Physics - Phenomenology