Generalized Limits to the Number of Light Particle Degrees of Freedom from Big Bang Nucleosynthesis

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dc.creatorOlive, Keith A.
dc.creatorThomas, David
dc.date1998-11-23
dc.date.accessioned2026-07-07T10:33:46Z
dc.date.available2026-07-07T10:33:46Z
dc.descriptionWe compute the big bang nucleosynthesis limit on the number of light neutrino degrees of freedom in a model-independent likelihood analysis based on the abundances of He4 and Li7. We use the two-dimensional likelihood functions to simultaneously constrain the baryon-to-photon ratio and the number of light neutrinos for a range of He4 abundances $Y_p$ = 0.225 -- 0.250, as well as a range in primordial Li7 abundances from (1.6 to 4.1) $ \times 10^{-10}$. For (Li7/H)$_p = 1.6 \times 10^{-10}$, as can be inferred from the Li7 data from Population II halo stars, the upper limit to $N_ν$ based on the current best estimate of the primordial He4 abundance of $Y_p = 0.238$, is $N_ν< 4.3$ and varies from $N_ν< 3.3$ (at 95% C.L.) when $Y_p=0.225$ to $N_ν< 5.3$ when $Y_p=0.250$. If Li7 is depleted in these stars the upper limit to $N_ν$ is relaxed. Taking (Li7/H)$_p = 4.1 \times 10^{-10}$, the limit varies from $N_ν< 3.9$ when $Y_p = 0.225$ to $N_ν\la 6$ when $Y_p = 0.250$. We also consider the consequences on the upper limit to $N_ν$ if recent observations of deuterium in high-redshift quasar absorption-line systems are confirmed.
dc.description9 pages, latex, 12 ps figures
dc.identifierhttps://arxiv.org/abs/hep-ph/9811444
dc.identifierhttp://arxiv.org/abs/hep-ph/9811444
dc.identifierAstropart.Phys.11:403-411,1999
dc.identifierdoi:10.1016/S0927-6505(99)00009-2
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/179237
dc.subjectHigh Energy Physics - Phenomenology
dc.subjectAstrophysics
dc.titleGeneralized Limits to the Number of Light Particle Degrees of Freedom from Big Bang Nucleosynthesis
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