Baryogenesis, sphalerons, and the cogeneration of dark matter

Processes involving the electroweak anomaly can erase completely a primordial baryon and lepton asymmetry if B-L=0. This has led to the search for plausible mechanisms for weak-scale baryogenesis, or for the generation of a primordial B-L asymmetry. Here it is emphasized that if another quantum number conserved up to anomalies is present electroweak anomaly processes would not necessarily erase a primordial baryon asymmetry even if B-L=0. Moreover, an asymmetry in the new quantum number that is comparable to the baryon asymmetry is generated concomitantly due to the electroweak anomaly. This asymmetry could be the origin of dark matter.