2020-05-18

UTAPwiki/セミナー/初期宇宙・相対論速報

Inhomogeneous nucleosynthesis †

Fumio Uchida †

A nonstandard model for big-bang nucleosynthesis (BBN) is introduced in this talk. The standard theory of BBN developed after the famous paper written in 1948 by R. Alpher, H. Bethe, and G. Gamow, to have achieved a great success in describing the abundance of light nuclei in our universe. However, there remain some open questions such as the Lithium 7 problem. Attempts to model inhomogeneous big-bang nucleosynthesis (IBBN) is introduced, and so are the motivations for it and latest results.
In the standard BBN (SBBN) theory, homogeneity and isotropy of the distribution of all the constituents is assumed, as is supported by the Planck observation at large scales. In the IBBN models, on the contrary, baryon isocurvature perturbations at small scales is taken into account. Some theories lead to this situation, and the theory of baryogengesis from a (hyper)magnetic field is introduced as an example. Most IBBN studies simply use a 2-phase model, and the resultant nuclei abundance can be different from that SBBN predicts.
References:
[1] J. F. Lara, Phys. Rev. D 72.2, 023509 (2005).
[2] B. D. Fields, et al. JCAP 2020.03, 010 (2020).
[3] R. A. Malaney, and G. J. Mathews, Phys. Rept. 229.4 145-219 (1993).