Deuterium and big-bang nucleosynthesis: implications for the baryon density

A new Monte Carlo technique is introduced to extract abundances and uncertainties in the framework of standard big-bang nucleosynthesis. Both very direct and less conservative, this method yields uncertainties in light element abundance predictions which are almost a factor of 3 smaller than that found with previous techniques. Key nuclear reaction rates are identified for which future nuclear cross-section measurements will further significantly reduce the abundance uncertainties. Finally, constraints on the baryon density inferred from BBN when combined with recent measurements of extragalactic deuterium yield Ωbh2=0.020±0.001 which agrees precisely with the latest constraints from power spectrum measurements of cosmic microwave background anisotropies.