2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/42531The evidence for neutrino oscillations leads to small neutrino masses, which can be realized by means of the seesaw mechanism. In this framework, baryogenesis may be achieved from leptogenesis.9 pages, RevTex4. Based on the talk presented at the Fourth International School of Physics "Bruno Pontecorvo", Capri, May 26-29, 2003High Energy Physics - Phenomenologytext