Neutron diffusion and nucleosynthesis

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The article discusses a new code for Big Bang Nucleosynthesis that incorporates neutron diffusion in a baryon inhomogeneous universe model. It highlights the significance of neutron diffusion timing relative to nucleosynthesis, impacting the final abundances of helium-4, deuterium, and lithium-7. The findings suggest that the baryon-to-photon ratio and depletion factors are larger than those in the Standard Big Bang Nucleosynthesis model, indicating potential limitations of the standard model's assumptions. The results align the constraints for helium-4 and deuterium while introducing a high depletion factor for lithium-7. This raises questions about the necessity of a baryon homogeneous universe post-inflation.
wolram
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http://arxiv.org/abs/astro-ph/0506364

Title: Neutron Diffusion and Nucleosynthesis in an Inhomogeneous Big Bang Model
Authors: Juan F. Lara
Comments: accepted for publication in Physical Review D

This article presents an original code for Big Bang Nucleosynthesis in a baryon inhomogeneous model of the universe. In this code neutron diffusion between high and low baryon density regions is calculated simultaneously with the nuclear reactions and weak decays that compose the nucleosynthesis process. The size of the model determines the time when neutron diffusion becomes significant. This article describes in detail how the time of neutron diffusion relative to the time of nucleosynthesis affects the final abundances of He4, deuterium and Li7. These results will be compared with the most recent observational constraints of He4, deuterium and Li7. This inhomogeneous model has He4 and deuterium constraints in concordance for baryon to photon ratio eta = (4.3 - 12.3) X 10^{-10} Li7 constraints are brought into concordance with the other isotope constraints by including a depletion factor as high as 5.9. These ranges for the baryon to photon ratio and for the depletion factor are larger than the ranges from a Standard Big Bang Nucleosynthesis model.
 
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wolram said:
http://arxiv.org/abs/astro-ph/0506364

Title: Neutron Diffusion and Nucleosynthesis in an Inhomogeneous Big Bang Model
Authors: Juan F. Lara
Comments: accepted for publication in Physical Review D
......
These ranges for the baryon to photon ratio and for the depletion factor are larger than the ranges from a Standard Big Bang Nucleosynthesis model.
Does that mean the standard BBN model has to be baryon homogeneous?

Garth
 
I think yes, but I am not sure. The universe is homogeneous after inflation. Why should it be 'baryon inhomogeneous'?
 
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