Cosmological implications of two conflicting deuterium abundances

Constraints on big bang nucleosynthesis (BBN) and on cosmological parameters from conflicting deuterium observations in different high redshift QSO systems are discussed. The high deuterium observations by Carswell et al., Songaila et al., and Rugers and Hogan are consistent with [Formula presented]He and [Formula presented]Li observations and standard BBN [Formula presented] =3) and allows [Formula presented] at 95% C.L., but are inconsistent with local observations of D and [Formula presented]He in the context of conventional theories of stellar and galactic evolution. In contrast, the low deuterium observations by Tytler, Fan, and Burles and Burles and Tytler are consistent with the constraints from local galactic observations, but require [Formula presented] at 68% C.L., excluding standard BBN at 99.9% C.L., unless the systematic uncertainties in the [Formula presented]He observations have been underestimated by a large amount. The high and low primordial deuterium abundances imply, respectively, [Formula presented]–[Formula presented] and [Formula presented]–[Formula presented] at 95% C.L. When combined with the high baryon fraction inferred from x-ray observations of rich clusters, the corresponding total mass densities (for [Formula presented] are [Formula presented]–[Formula presented] and [Formula presented]–[Formula presented], respectively (95% C.L.). The range of [Formula presented] corresponding to high D is in conflict with dynamical constraints [Formula presented]–[Formula presented] and with the shape parameter constraint [Formula presented] from large scale structure formation in CDM and [Formula presented]CDM models.