Baryogenesis and supersymmetric GUTs

We examine baryogenesis in the context of supersymmetric GUTs. In this regard, there are four important differences between GUTs and supersymmetric GUTs: the latter have double the number of particle species, larger unified coupling constant, possibility of dimension-five operators which violate baryon number and a higher unification scale. The first three of these differences lead to the increased importance of 2reversible2 B nonconserving scatterings, which, for a given superheavy gauge or Higgs mass, result in a smaller baryon asymmetry than for a non-supersymmetric GUT. Of these differences, dimension-five operators (if they exist) are the most important, and can lead to a substantially smaller baryon asymmetry than in the non-supersymmetric case. (orig.)