I will discuss recent developments in applications of generalised unitarity to multi-particle one-loop processes. Such techniques allow useful insight into the structure of general gauge theory and provide efficient techniques for analytic and numerical computations. As a demonstration of this I will describe computations for massive quark production in QCD and of multi-photon amplitudes in QED. We will see that the latter can be shown to have a “no-triangle” property similar to that seen in N=8 super-gravity.

DESY-Zeuthen