2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/97408An analytical approach is applied to the calculation of some dimensionally-regulated two-loop vertex diagrams with essential on-shell singularities. Such diagrams are important for the evaluation of QED corrections to the muon decay, QCD corrections to top quark decays t->W^{+}b, t->H^{+}b, etc.2 pages, LaTeX, contribution to proceedings of ACAT2002 (Moscow, June 2002)High Energy Physics - Phenomenologytext