Precision prediction for the big-bang abundance of primordial He-4 - art. no. 103502

Within the standard models of particle physics and cosmology we have calcul ated the big-bang prediction for the primordial abundance of He-4 to a theo retical uncertainty of less than 0.1% (delta Y-P < +/-0.0002), improving th e current theoretical precision by a factor of 10. At this accuracy the unc ertainty in the abundance is dominated by the experimental uncertainty in t he neutron mean lifetime, tau(n) = 885.4 +/- 2.0 sec. The following physica l effects were included in the calculation: the zero and finite-temperature radiative, Coulomb and finite-nucleon-mass corrections to the weak rates; order-alpha quantum-electrodynamic correction to the plasma density, electr on mass, and neutrino temperature; and incomplete neutrino decoupling. New results for the finite-temperature radiative correction and the QED plasma correction were used. In addition, we wrote a new and independent nucleosyn thesis code designed to control numerical errors to be less than 0.1%. Our predictions for the He-4 abundance are presented in the form of an accurate fitting formula. Summarizing our work in one number, Y-P(eta = 5 X 10(-10) ) = 0.2462 +/- 0.0004 (expt) +/- <0.0002 (theory). Further, the baryon dens ity inferred from the Burles-Tytler determination of the primordial D abund ance, Omega(B)h(2) = 0.019 +/- 0.001, leads to the prediction Y-P = 0.2464 +/- 0.0005 (D/H) +/- <0.0002 (theory) +/-0.0005 (expt). This "prediction" a nd an accurate measurement of the primeval He-4 abundance will allow an imp ortant consistency test of primordial nucleosynthesis. [S0556-2821(99)05106 -1].