Baryogenesis through collapsing string loops in gauged baryon and lepton models.

A scenario for the generation of the baryon asymmetry in the early Universe is proposed in which cosmic string loops, predicted by theories where the baryon and/or lepton numbers are gauged symmetries, collapse during the friction dominated period of string evolution. This provides a mechanism for the departure from thermal equilibrium necessary to have a nonvanishing baryon asymmetry. Examples of models are given where this idea can be implemented. In particular, the model with the gauge symmetry SU(3)c⊗SU(2)L⊗U(1)Y ⊗U(1)B ⊗U(1)L has the interesting feature where sphaleron processes do not violate the baryon and lepton numbers so that no wash out of any initial baryon asymmetry occurs at the electroweak scale. email: lew%[email protected] email: [email protected]