Experimental, computational, and observational analysis of primordial nucleosynthesis
We have made a comprehensive evaluation of the standard theory of primordial nucleosynthesis, by (a) determining the nuclear reactions most important for light element production in the Big Bang; (b) conducting a detailed study of the rates and uncertainties of these reactions (c) employing a Monte Carlo analysis to properly evaluate uncertainties in the computed elemental abundances arising from reaction rate uncertainties; and (d) comparing the predicted abundances of d, {sup 3}He, {sup 4}He, and {sup 7}Li to those inferred from observations. We find a consistent agreement for 2.68 {times} 10{sup {minus}10} {le} {eta} {le} 3.77 {times} 10{sup {minus}10}, where {eta} is the baryon-to-photon ratio, thereby supporting the standard Big Bang nucleosynthesis (SBBN) theory. The corresponding constraint on the baryon density parameters is 0.01 {le} {Omega}{sub b} {le} 0.09, where the primordial d+{sup 3}He ({sup 4}He) abundance sets the lower (upper) bound. We find that the new reaction rates increase the {eta} upper bound from {sup 7}Li by 45%, and that inconsistencies in SBBN will arise if the primordial {sup 4}He mass fraction is less than 0.237 or if the primordial {sup 7}Li abundance is at the Pop I level. For slightly non-standard primordial nucleosynthesis models, comparisons to primordial abundances show that the number of neutrino families N{sub nu} is limited to N{sub nu} {le} 3.3. Specifically, 3.5 neutrino families (3 Dirac {nu}`s plus one Majorana {nu}) or more are ruled out at the 2-{sigma} level. The dependence of the N{sub nu} upper limit on the abundances limits has been parameterized.
- Research Organization:
- Oak Ridge National Lab., TN (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States); National Science Foundation, Washington, DC (United States)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 10125272
- Report Number(s):
- CONF-9209239--5; ON: DE93006626; CNN: Grant PHY88-17296; Grant PHY91-15574
- Country of Publication:
- United States
- Language:
- English
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71 CLASSICAL AND QUANTUM MECHANICS
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