An Accurate Calculation of the Big Bang Prediction for the Abundance of Primordial Helium

Jul, 1998
28 pages
Published in:
  • Phys.Rev.D 59 (1999) 103502
e-Print:
Report number:
  • FERMILAB-PUB-98-232-A

Citations per year

19982005201220192025051015
Abstract: (arXiv)
Within the standard models of particle physics and cosmology we have calculated the big-bang prediction for the primordial abundance of \he to a theoretical uncertainty of less than 0.1 \pct (δYP<±0.0002)(\delta Y_P < \pm 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, τn=885.4±2.0sec\tau_n = 885.4 \pm 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-α\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\pct. Our predictions for the \EL[4]{He} abundance are presented in the form of an accurate fitting formula. Summarizing our work in one number, YP(η=5×1010)=0.2462±0.0004(expt)±<0.0002(theory) Y_P(\eta = 5\times 10^{-10}) = 0.2462 \pm 0.0004 (expt) \pm < 0.0002 (theory). Further, the baryon density inferred from the Burles-Tytler determination of the primordial D abundance, ΩBh2=0.019±0.001\Omega_B h^2 = 0.019\pm 0.001, leads to the prediction: YP=0.2464±0.0005(D/H)±<0.0002(theory)±0.0005(expt)Y_P = 0.2464 \pm 0.0005 (D/H) \pm < 0.0002 (theory) \pm 0.0005 (expt). This ``prediction'' and an accurate measurement of the primeval \he abundance will allow an important consistency test of primordial nucleosynthesis.
  • cosmological model
  • light nucleus: production
  • helium
  • electron nucleon: interaction
  • radiative correction: finite temperature
  • correction: Coulomb
  • nucleon: mass
  • mass: correction
  • plasma: density
  • electron: mass