Big-Bang Nucleosynthesis Predictions for Precision Cosmology

TL;DR

This work delivers analytic, precision-era Big-Bang Nucleosynthesis predictions by linking light-element yields to experimental nuclear-data uncertainties through a large Monte Carlo framework. It provides fifth-order polynomial fits for the means, variances, and covariances of abundances as a function of $\eta$ (via $x=\log_{10}\eta+10$), and splits $^7$Li production into direct and $^7$Be- to-$^7$Li channels to capture distinct contributions. By combining a precisely measured primordial deuterium abundance with ISM D+$^3$He and $^7$Li and $^4$He data, the authors infer $\eta=(5.5\pm0.5)\times10^{-10}$ and $\Omega_B h^2=0.020\pm0.002$ (95% cl), while identifying a Lithium problem that requires a depletion factor $f_7\approx0.32$ (95% conf $0.20$–$0.55$). The results support a low baryon density compatible with, though mildly contested by, CMB-derived values and underscore remaining systematic uncertainties in $^4$He and $^7$Li measurements, motivating improved nuclear inputs and stellar/luminosity modeling.

Abstract

The determination of the primeval deuterium abundance has opened a precision era in big-bang nucleosynthesis (BBN), making accurate predictions more important than ever before. We present in analytic form new, more precise predictions for the light-element abundances and their error matrix. Using our predictions and the primeval deuterium abundance we infer a baryon density of Omega_B h^2 = 0.020 pm 0.002 (95% cl) and find no evidence for stellar production (or destruction) of 3He beyond burning D to 3He. Conclusions about 4He and 7Li currently hinge upon possible systematic error in their measurements.