New Bounds on Omega Baryons from Observational Big Bang Nucleosynthesis

We re-examine the systematic errors in the determination of the primordial helium abundance, $Y_{\mathrm{P}}$. We find that the systematics are significantly larger than the statistical errors. The uncertainty in (the determination of) $Y_{\mathrm{P}}$, is thus, larger than is currently claimed. Furthermore, most of the systematics lead to underestimate of $Y_{\mathrm{P}}$. The new upper bound allows cosmological models with no non-baryonic dark matter in which ${\mathrm{\Omega }}_{baryons}={\mathrm{\Omega }}_{BBN}={\mathrm{\Omega }}_{dyn}$.