2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/217941We calculate all the four-photon helicity amplitudes at the one-loop level in a massive theory using multiple-cut methods. The amplitudes are derived in scalar QED, QED and $\textrm{QED}^{\caln =1}$ theories. We will see the origin of rational terms. We extend the calculation to the simplest six-photon helicity amplitude where all photons have the same helicity.32 pages, 42 diagrams, adds referencesHigh Energy Physics - Phenomenologytext