Experimental, computational, and observational analysis of primordial nucleosynthesis

Conference · Thu Dec 31 04:00:00 EST 1992

OSTI ID:10125272

Smith, M S

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

Related Subjects

661300
663300
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
COSMOLOGICAL MODELS
ELEMENT ABUNDANCE
MONTE CARLO METHOD
NEUTRINOS
NUCLEAR REACTION KINETICS
NUCLEAR REACTIONS
NUCLEAR REACTIONS AND SCATTERING
GENERAL
NUCLEOSYNTHESIS
OTHER ASPECTS OF PHYSICAL SCIENCE