Loops in Twistor Space
arXiv:hep-th/0410054 · doi:10.1103/PhysRevD.71.106010
Abstract
We elucidate the one-loop twistor-space structure corresponding to momentum-space MHV diagrams. We also discuss the infrared divergences, and argue that only a limited set of MHV diagrams contain them. We show how to introduce a twistor-space regulator corresponding to dimensional regularization for the infrared-divergent diagrams. We also evaluate explicitly the `holomorphic anomaly' pointed out by Cachazo, Svrcek, and Witten, and use the result to define modified differential operators which can be used to probe the twistor-space structure of one-loop amplitudes.
21 pages, TeX. v3. missing citations added. v4. subtlety with the i εprescription clarified