Primordial nucleosynthesis as a probe of particle physics and cosmology
In this dissertation, the author uses the success of the standard model of big-bang nucleosynthesis to examine the effects of interacting particle species and the effect of varying coupling constants, predicted by theories set in extra dimensions, on primordial nucleosynthesis. A review is given of the standard model and of the abundances of the light elements expected to be produced in the early Universe. The weakest piece of the concordance between the standard model of big-bang nucleosynthesis and observation is the production and primordial abundance of {sup 7}Li. Therefore he discusses the production of {sup 7}Li in astrophysical environments other than the early Universe and shows that the predictions of big-bang nucleosynthesis, when supplemented by those due to astrophysical sources, are in good agreement with observation. He then shows that the effect on big-bang nucleosynthesis of an additional particle species which remains coupled to either photons or light neutrinos can be quite different from that predicted by the equivalent number of neutrino species parameterization, which does work for decoupled additional species. In particular he considers the case of an additional axion-like particle and shows that its effect is to decrease the amount of {sup 4}He produced in the big-bang. In addition, he considers the effects of varying coupling constants on {sup 4}He production in the big-bang and shows that constraining Y{sub p} = 0.24 {plus minus} 0.01 leads to a constraint on the time variation of the fine-structure constant of {vert bar}dln {alpha}/dt{vert bar} {le} {times} 10{sup {minus}14}.
- Research Organization:
- Indiana Univ., Bloomington, IN (USA)
- OSTI ID:
- 5667243
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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640106* - Astrophysics & Cosmology- Cosmology