A reexamination of the effects of non-zero neutrino degeneracies on big bang nucleosynthesis is made. As previously noted, non-trivial alterations of the standard model conclusions can only be induced if excess lepton numbers Li, comparable to photon number densities nγ, are assumed (where nγ∼3×109nb). Furthermore, the required lepton number densities (Linγ) must be different for νe than for νμ and ντ. It is shown that this loophole in the standard model of nucleosynthesis is robust and will not vanish as abundance and reaction rate determinations improve. However, it is also argued that theoretically | Le | ∼ | Lμ | ∼ | Lτ | ∼ nb ≪ nγ which would preclude this loophole in standard unified models.
Bibliographical noteFunding Information:
We would like to thank H.S. Kang, E.W. Kolb, G. Steigman and M.S. Turner for useful discussions. This work was supported in part by the NSF (AST88-20595) and NASA (NAGW-1321 ) at Chicago, by the DOE and NASA at Fermilab, and by the DOE (DE-AC02-83ER40105 ) at Minnesota; the work of K.A.O. is also supported in part by an NSF PYI Award.