2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/49014The consistent description of unstable particles within the framework of perturbative gauge field theories necessitates the definition and resummation of off-shell Green's functions, which must respect several crucial physical requirements. We present the solution to this problem at one-loop, using the pinch technique.11 pages, uses revtex, 7 Figures in separate ps file, contribution to the 1998 Corfu Summer Institute on Elementary Particle Physics (JHEP proceedings)High Energy Physics - Phenomenologytext