2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/44910We investigate the prospects of an extra global symmetry, added to the Standard Model in the context of baryogenesis. The $PQ$ symmetry is studied as an example. We show that the hadronic axion provides a protection of the B-asymmetry even if $B-L$=0 and that there are no limits on the neutrino masses. It is also shown that there is a crucial difference between the two possible invisible axion models. A connection between the baryon asymmetry and dark matter is also pointed out.8 pages, Latex, Preprint SNUTP-93-40High Energy Physics - Phenomenologytext