2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/188366Massive on-shell operator matrix elements and self-energy diagrams with outer gluon lines are calculated analytically at $O(α_s^2)$, using Mellin-Barnes integrals and representations through generalized hypergeometric functions. This method allows for a direct evaluation without decomposing the integrals using the integration-by-parts method.1 Latex file, 1 style file, 3 figuresHigh Energy Physics - Phenomenologytext