期刊
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
卷 -, 期 3, 页码 -出版社
IOP Publishing Ltd
DOI: 10.1088/1475-7516/2020/03/010
关键词
big bang nucleosynthesis; cosmological parameters from CMBR; cosmological neutrinos
资金
- National Science Foundation [PHY-1214082, PHY-1430152]
- DOE at the University of Minnesota [DE-SC0011842]
- Office of Science, Office of High Energy Physics of the U.S. Department of Energy [DE-AC02-05CH11231]
- Department of Physics
- high energy theory group at the University of California, Berkeley
- theory group at LBNL
We assess the status of big-bang nucleosynthesis (BBN) in light of the final Planck data release and other recent developments, and in anticipation of future measurements. Planck data from the recombination era fix the cosmic baryon density to 0.9% precision, and now damping tail measurements determine the helium abundance and effective number of neutrinos with precision approaching that of astronomical and BBN determinations respectively. All three parameters are related by BBN. In addition, new high-redshift measurements give D/H to better precision than theoretical predictions, and new Li/H data reconfirm the lithium problem. We present new Be-7(n, p)(7) Li rates using new neutron capture measurements; we have also examined the effect of proposed changes in the d(p, gamma)He-3 rates. Using these results we perform a series of likelihood analyses. We assess BBN/CMB consistency, with attention to how our results depend on the choice of Planck data, as well as how the results depend on the choice of non-BBN, non-Planck data sets. Most importantly the lithium problem remains, and indeed is more acute given the very tight D/H observational constraints; new neutron capture data reveals systematics that somewhat increases uncertainty and thus slightly reduces but does not essentially change the problem. We confirm that d(p, gamma)(3) He theoretical rates brings D/H out of agreement and slightly increases Li-7; new experimental data are needed at BBN energies. Setting the lithium problem aside, we find the effective number of neutrino species at BBN is N-nu = 2.86 +/- 0.15. Future CMB Stage-4 measurements promise substantial improvements in BBN parameters: helium abundance determinations will be competitive with the best astronomical determinations, and N-eff will approach sensitivities capable of detecting the effects of Standard Model neutrino heating of the primordial plasma.
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