A reexamination of the cosmological bound to the number of neutrino flavors

G. Steigman, K. A. Olive, D. N. Schramm, M. S. Turner

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The predictions of the light element abundances produced primordially in the standard hot big bang cosmological model with three species of light neutrinos (Nν=3) is consistent with current observational data. If additional species of light neutrinos exist, additional 4He is produced primordially; consistency with observations of 4He leads to an upper bound to Nν which depends on the neutron half-life (τ 1 2), the nucleon-to-photon ratio (or, equivalently, the primordial abundances of deuterium and helium-3) and the primordial mass fraction of 4He (Yp). The bounds to these quantities are reexamined and Nν≤4.0 is reconfirmed.

Original languageEnglish (US)
Pages (from-to)33-38
Number of pages6
JournalPhysics Letters B
Issue number1-2
StatePublished - Aug 21 1986

Bibliographical note

Funding Information:
NSF and the DOE and, at Fermilab their research is supported by NASA.

Funding Information:
The research of Gary Steigman is supported at Bartol by the DOE (DE-AC02-78ER-05007), that of K.A.O. is supported at Minnesota also by the DOE (DE-AC02-83ER-40105), at Chicago the research of D.N.S. and M.S.T. is supported by the


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