Calculating one-loop multileg processes

Abstract

This study is targeted to the calculation of NLO QCD corrections to multileg processes that are important for the LHC. Starting from the construction of Feynman diagrams, the analytical reduction of general one-loop integrals to scalar master ones, the calculation of colour structures, and finally phase space point selection are reviewed, in a program producing Fortran code for numerical calculation of one-loop corrections for processes like gg → tt, gg → ttg and gg → ttgg.