Neutrino degeneracy and cosmological nucleosynthesis, revisited

Keith A. Olive; David N. Schramm; David Thomas; Terry P. Walker

doi:10.1016/0370-2693(91)90048-U

Neutrino degeneracy and cosmological nucleosynthesis, revisited

Keith A. Olive, David N. Schramm, David Thomas, Terry P. Walker

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Abstract

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 L_i, comparable to photon number densities n_γ, are assumed (where n_γ∼3×10⁹n_b). Furthermore, the required lepton number densities (L_in_γ) must be different for ν_e than for ν_μ and ν_τ. 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 | L_e | ∼ | L_μ | ∼ | L_τ | ∼ n_b ≪ n_γ which would preclude this loophole in standard unified models.

Original language	English (US)
Pages (from-to)	239-244
Number of pages	6
Journal	Physics Letters B
Volume	265
Issue number	3-4
DOIs	https://doi.org/10.1016/0370-2693(91)90048-U
State	Published - Aug 15 1991

Bibliographical note

Funding 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.

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title = "Neutrino degeneracy and cosmological nucleosynthesis, revisited",

abstract = "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.",

author = "Olive, {Keith A.} and Schramm, {David N.} and David Thomas and Walker, {Terry P.}",

note = "Funding 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.",

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AU - Olive, Keith A.

AU - Schramm, David N.

AU - Thomas, David

AU - Walker, Terry P.

N1 - Funding 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.

PY - 1991/8/15

Y1 - 1991/8/15

N2 - 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.

AB - 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.

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JO - Physics Letters B

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Neutrino degeneracy and cosmological nucleosynthesis, revisited

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