Lepton degeneracy and cosmological constraints on the number of neutrinos

It is shown that the possible loophole of neutrino degeneracy in the cosmological arguments constraining the number of neutrino types is unlikely to be significant. For degeneracy to be important, the electron neutrino number (ΔNsub(γsub(e))=Nsub(γsub(e))-Nsub(anti γsub(e))) must be some nine orders of magnitude larger than the baryon number (ΔB) whereas in the context of baryon and lepton number violating grand unified theories it is expected that ΔNsub(γsub(e)) approximately ΔB. (Auth.)