Sharpening the Predictions of Big-Bang Nucleosynthesis

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 D, ³He, and ⁷Li. 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 ΩBh²0ex0ex=0ex0ex0.019±0.0024, predict a primeval ⁴He mass fraction YP0ex0ex=0ex0ex0.246±0.0014, and obtain a limit to the equivalent number of neutrino species N_ν<3.20 (all at $95%$ C.L.). We also identify key reactions and the energies, where improved data would allow further progress.