2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/190701We derive recurrence relations between phase space expressions in different dimensions by confining some of the coordinates to tori or spheres of radius $R$ and taking the limit as $R \to \infty$. These relations take the form of mass integrals, associated with extraneous momenta (relative to the lower dimension), and produce the result in the higher dimension.13 pages, Latex, to appear in J Phys AHigh Energy Physics - Theorytext