2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/45542We expose a grave drawback hidden in the standard model of neutron-antineutron transitions in a medium. Correcting it, one improves a limit on the free-space neutron-antineutron oscillation time by 31 orders of magnitude.7 pages, LATEXHigh Energy Physics - PhenomenologyNuclear Theorytext