Big bang nucleosynthesis

Brian D. Fields, Keith A. Olive

Research output: Contribution to journalArticlepeer-review


We present an overview of the standard model of big bang nucleosynthesis (BBN), which describes the production of the light elements in the early universe. The theoretical prediction for the abundances of D, 3He, 4He, and 7Li is discussed. We emphasize the role of key nuclear reactions and the methods by which experimental cross section uncertainties are propagated into uncertainties in the predicted abundances. The observational determination of the light nuclides is also discussed. Particular attention is given to the comparison between the predicted and observed abundances, which yields a measurement of the cosmic baryon content. The spectrum of anisotropies in the cosmic microwave background (CMB) now independently measures the baryon density to high precision; we show how the CMB data test BBN, and find that the CMB and the D and 4He observations paint a consistent picture. This concordance stands as a major success of the hot big bang. On the other hand, 7Li remains discrepant with the CMB-preferred baryon density; possible explanations are reviewed. Finally, moving beyond the standard model, primordial nucleosynthesis constraints on early universe and particle physics are also briefly discussed.

Original languageEnglish (US)
Pages (from-to)208-225
Number of pages18
JournalNuclear Physics A
StatePublished - Oct 17 2006

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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