The six-photon amplitude

Abstract

Thanks to the absence of tree order, the six-photon processes is a good laboratory to study multi-leg one-loop diagrams. Particularly, there are enough on-shell external legs to observe a special Landau singularity: the double parton scattering.

Comments: 4 pages, 5 figures, talk given at 43nd Rencontres de Moriond on QCD and High-Energy Interactions, La Thuile, March 2007