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arXiv · hep-ph/9610319

A Big Bang Nucleosynthesis Likelihood Analysis of the Baryon-to-Photon Ratio and the Number of Light Particle Degrees of Freedom

Keith A. Olive·David Thomas
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Abstract

We extend the model-independent likelihood analysis of big bang nucleosynthesis (BBN) based on He4 and Li7 to allow for numbers of degrees of freedom which differ from the standard model value characterized by $N_ν= 3$. We use the two-dimensional likelihood functions to simultaneously constrain the baryon-to-photon ratio and the number of light neutrinos. The upper limit thus obtained is $N_ν< 4.0$ (at 95% C.L.). We also consider the consequences if recent observations of deuterium in high-redshift QSO absorption-line systems (QSOALS) are confirmed.

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Keith A. Olive, David Thomas. 1996-10-10. A Big Bang Nucleosynthesis Likelihood Analysis of the Baryon-to-Photon Ratio and the Number of Light Particle Degrees of Freedom. https://doi.org/10.1016/s0927-6505(97)00008-x

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