In International Journal of Modern Physics E, Volume 15, Issue 01, pp. 1-35 (2006)
astro-ph/0511534

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PRIMORDIAL NUCLEOSYNTHESIS: SUCCESSES AND CHALLENGES

Gary Steigman


Abstract. Primordial nucleosynthesis provides a probe of the Universe during its early evolution. Given the progress exploring the constituents, structure, and recent evolution of the Universe, it is timely to review the status of Big Bang Nucleosynthesis (BBN) and to confront its predictions, and the constraints which emerge from them, with those derived from independent observations of the Universe at much later epochs in its evolution. Following an overview of the key physics controlling element synthesis in the early Universe, the predictions of the standard models of cosmology and particle physics are presented, along with those from some non-standard models. The observational data used to infer the primordial abundances are described, with an emphasis on the distinction between precision and accuracy. These relic abundances are compared with predictions, testing the internal consistency of BBN and enabling a comparison of the BBN constraints with those derived from the WMAP Cosmic Background Radiation data. Emerging from these comparisons is a successful standard model along with constraints on (or hints of) physics beyond the standard models of particle physics and of cosmology.


Keywords Big Bang Nucleosynthesis; Early Universe Expansion Rate; Neutrino Asymmetry; Abundances of D, 3He, 4He, 7Li.


Table of Contents

INTRODUCTION
Baryon Asymmetry - Nucleon Abundance
The Expansion Rate At BBN
Neutrino Asymmetry

AN OVERVIEW OF PRIMORDIAL NUCLEOSYNTHESIS
Nonstandard BBN
Simple - But Accurate - Fits To The Primordial Abundances
SBBN-Predicted Primordial Abundances

OBSERVATIONALLY INFERRED PRIMORDIAL ABUNDANCES
The Primordial Deuterium Abundance
The Primordial Helium-3 Abundance
The Primordial Helium-4 Abundance
The Primordial Lithium-7 Abundance

DISCUSSION
SBBN
Lithium
Non-Standard Expansion Rate: S neq 1 (xie = 0)
Non-Zero Lepton Number: xie neq 0 (S = 1)
An Example: Alternate Relic Abundances for D and 4He
Other Non-Standard Models

SUMMARY AND CONCLUSIONS

REFERENCES

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