2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/201348We exploit the fact that, in Minkowski space-time, gamma matrices are possibly more fundamental than the metric to describe how gauge invariance at perturbative level enforces a Lagrangian for spinor electrodynamics with massless photons. The term quadratic in the potential arises naturally in the gauge-fixed Lagrangian but has vanishing coefficient.5 pages, Plain TexHigh Energy Physics - Phenomenologytext