Electron-photon interaction: Feynman diagrams and contact points

Abstract

In this note, we formulate the notions of the direct and inverse problems and contact points for the Feynman diagrams. For the electron-photon interaction case, the solutions of these direct and inverse problems are presented. The interrelations between Feynman diagrams and the classical colored graphs are discussed.

This note is a prolongation of our works arXiv:2511.02847 and arXiv:2604.11612 on Feynman's theory although in a somewhat different context