2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/39279We discuss current theoretical and experimental issues associated with the recent SuperKamiokande discovery. We survey theoretical models for predictings the new Standard Model parameters needed to explain this discovery, and point out how quark-lepton symmetries, either in the framework of Grand Unification, or of string theories, can be used to determine them.Invited Talk at the XI Rencontre de Blois, June 27-July 3, 1999. Latex, 11 pagesHigh Energy Physics - Phenomenologytext