Sharpening the Predictions of Big-Bang Nucleosynthesis

Abstract

We have reexamined the nuclear inputs to big-bang nucleosynthesis using Monte Carlo realization of the cross-section data to directly estimate theoretical uncertainties for the yields of $\mathrm{D}$, ${}^{3}\mathrm{He}$, and ${}^{7}\mathrm{Li}$. Our results indicate that previous estimates of the uncertainties were too large by a factor of 2. Using the Burles--Tytler deuterium measurement, we infer a baryon density ${\ensuremath{\Omega}}_{B}{h}^{2}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.019\ifmmode\pm\else\textpm\fi{}0.0024$, predict a primeval ${}^{4}\mathrm{He}$ mass fraction ${Y}_{P}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.246\ifmmode\pm\else\textpm\fi{}0.0014$, and obtain a limit to the equivalent number of neutrino species ${N}_{\ensuremath{\nu}}<3.20$ (all at $95%$ C.L.). We also identify key reactions and the energies, where improved data would allow further progress.