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 , {sup 3}He , and {sup 7}Li . Our results indicate that previous estimates of the uncertainties were too large by a factor of 2. Using the Burles{endash}Tytler deuterium measurement, we infer a baryon density {Omega}{sub B}h{sup 2}=0.019{plus_minus}0.0024 , predict a primeval {sup 4}He mass fraction Y{sub P}=0.246{plus_minus}0.0014 , and obtain a limit to the equivalent number of neutrino species N{sub {nu}}{lt}3.20 (all at 95{percent} C.L.). We also identify key reactions and the energies, where improved data would allow further progress. {copyright} {ital 1999} {ital The American Physical Society}