Strings and Supersymmetry as Tools for Perturbative QCD

Abstract

We review techniques simplifying the analytic calculation of one-loop QCD amplitudes with many external legs, for use in next-to-leading-order corrections to multi-jet processes. We explain how a supersymmetry-inspired organization works well in conjunction with other tools, namely the color and helicity decompositions of amplitudes, and the constraints imposed by perturbative unitarity and collinear singularities. String theory seems most useful as a heuristic guide. Using these techniques, the complete set of one-loop five-parton QCD amplitudes, as well as certain sequences of special helicity amplitudes with an arbitrary number of external gluons, have been obtained.