2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/207520We suggest that the discrepant lifetime measurements of ortho-positronium can be explained by ortho-positronium oscillations into mirror ortho-positronium. This explanation can be tested in future vacuum experiments.about 6 pages, Latex, to appear in Phys.Lett.BHigh Energy Physics - Phenomenologytext