Derivation of the Cross-Free Family representation for the box diagram

Abstract

I work out in full detail the derivation of the Cross-Free Family (CFF) representation for the box diagram, and highlight the differences with its Time Ordered Perturbation Theory (TOPT) representation. I briefly discuss implications for the threshold singularity structure of the diagram.

Comments: Proceedings for RADCOR 2023 - 16th International Symposium on Radiative Corrections: Applications of Quantum Field Theory to Phenomenology, Sunday 28th May 2023 - Friday 2nd June 2023, Crieff, Scotland