Precision prediction for the big-bang abundance of primordial {sup 4}He
- Department of Physics, The University of Chicago, Chicago, Illinois 60637-1433 (United States)
Within the standard models of particle physics and cosmology we have calculated the big-bang prediction for the primordial abundance of {sup 4}He to a theoretical uncertainty of less than 0.1{percent} ({delta}Y{sub P}{lt}{plus_minus}0.0002), improving the current theoretical precision by a factor of 10. At this accuracy the uncertainty in the abundance is dominated by the experimental uncertainty in the neutron mean lifetime, {tau}{sub n}=885.4{plus_minus}2.0 sec. The following physical 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, electron 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 nucleosynthesis code designed to control numerical errors to be less than 0.1{percent}. Our predictions for the {sup 4}He abundance are presented in the form of an accurate fitting formula. Summarizing our work in one number, Y{sub P}({eta}=5{times}10{sup {minus}10})=0.2462{plus_minus}0.0004 (expt)thinsp{plus_minus}{lt}0.0002 (theory). Further, the baryon density inferred from the Burles-Tytler determination of the primordial D abundance, {Omega}{sub B}h{sup 2}=0.019{plus_minus}0.001, leads to the prediction Y{sub P}=0.2464{plus_minus}0.0005 (D/H)thinsp{plus_minus}{lt}0.0002 (theory)thinsp{plus_minus}0.0005 (expt). This {open_quotes}prediction{close_quotes} and an accurate measurement of the primeval {sup 4}He abundance will allow an important consistency test of primordial nucleosynthesis. {copyright} {ital 1999} {ital The American Physical Society}
- OSTI ID:
- 348211
- Journal Information:
- Physical Review, D, Vol. 59, Issue 10; Other Information: PBD: May 1999
- Country of Publication:
- United States
- Language:
- English
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