Big-bang nucleosynthesis

Journal article

A critical review is given of the current status of cosmological nucleosynthesis. In the framework of the Standard Model with 3 types of relativistic neutrinos, the baryon-to-photon ratio, $\eta$, corresponding to the inferred primordial abundances of deuterium and helium-4 is consistent with the independent determination of $\eta$ from observations of anisotropies in the cosmic microwave background. However the primordial abundance of lithium-7 inferred from observations is significantly below its expected value. Taking systematic uncertainties in the abundance estimates into account, there is overall concordance in the range $\eta = (5.7-6.7)\times 10^{-10}$ at 95% CL (corresponding to a cosmological baryon density $\Omega_B h^2 = 0.021 - 0.025$). The D and He-4 abundances, when combined with the CMB determination of $\eta$, provide the bound $N_\nu=3.28 \pm 0.28$ on the effective number of neutrino species. Other constraints on new physics are discussed briefly.

Authors: Fields, B; Molaro, P; Sarkar, S

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: IOP Publishing
• Journal: Chinese Physics C
• Volume: 38
• Issue: 9
• Article number: 090001
• Publication date: 2014-01-08
• DOI: 10.1088/1674-1137/38/9/090001
• ISSN: 1674-1137
• Language: English
• Keywords: astro-ph.CO