An overview of the standard model of big bang nucleosynthesis (BBN) in the post-WMAP era is presented. With the value of the baryon-to-photon ratio determined to relatively high precision by WMAP, standard BBN no longer has any free parameters. In this context, the theoretical prediction for the abundances of D, He4, and Li7 is discussed and compared to the observational determination of the light nuclides. While concordance for D is excellent, and acceptable within the uncertainties for He4, the prediction for Li7 exceeds the observational determination by a factor of about four. Possible solutions to this problem are also discussed.

University of Minnesota