Abstract

Recently, it has been shown that in gauge theories amplitudes to any perturbation order can be obtained by gluing together simple three-point on-shell amplitudes. These three-point amplitudes, in turn, are fixed by locality and Lorentz invariance. This factorization into three-point on-shell amplitudes follows from the Britto-Cachazo-Feng-Witten recursion relations and the Feynman-tree theorem. In an explicit example, that is, the four-gluon amplitude with all plus helicities, we illustrate the method. In a conventional calculation, this amplitude corresponds to one-loop box diagrams.