Calculating Scattering Amplitudes Efficiently

Abstract

We review techniques for more efficient computation of perturbative scattering amplitudes in gauge theory, in particular tree and one-loop multi-parton amplitudes in QCD. We emphasize the advantages of (1) using color and helicity information to decompose amplitudes into smaller gauge-invariant pieces, and (2) exploiting the analytic properties of these pieces, namely their cuts and poles. Other useful tools include recursion relations, special gauges and supersymmetric rearrangements.

Comments: LaTex, 45 pages with 11 encapsulated figures. Presented at the Theoretical Advanced Study Institute (TASI 95), Boulder, CO, June 4-30, 1995. Eqs. (29) and (55), and postscript bug fixed