2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/39646Positronium decay rates are computed at the one-loop level, using convolution-type factorized amplitudes. The dynamics of this factorization is probed with dispersion relations, showing that unallowed approximations are usually made, and some ordre alpha^2 corrections missed. Further, we discuss the relevance of the Schrodinger wavefunction as the basis for perturbative calculations. Finally, we apply our formalism to the parapositronium two-photon decay.LaTeX, 13 pages, 1 eps figureHigh Energy Physics - Phenomenologytext