2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/188283The main idea of the first order formalism is demonstrated on a toy example of spin-0 particle. The full formalism for spin-1 is applied to the vector formfactor of the pion and its high-energy behaviour is studied.6 pages, 1 figure; presented by K.K. at Final Euridice MeetingHigh Energy Physics - Phenomenologytext