COSMOLOGICAL IMPLICATIONS OF 2 CONFLICTING DEUTERIUM ABUNDANCES

Constraints on big bang nucleosynthesis (BBN) and on cosmological para meters from conflicting deuterium observations in different high redsh ift QSO systems are discussed. The high deuterium observations by Cars well el al., Songaila et al., and Rugers and Hogan are consistent with He-4 and Li-7 observations and standard BBN (N-v = 3) and allows N-v less than or equal to 3.6 at 95% C.L., but are inconsistent with local observations of D and He-3 in the context of conventional theories of stellar and galactic evolution. In contrast, the low deuterium observ ations by Tytler, Fan, and Buries and Buries and Tytler are consistent with the constraints from local galactic observations, but require N- v=1.9+/-0.3 at 68% C.L., excluding standard BBN at 99.9% C.L., unless the systematic uncertainties in the He-4 observations have been undere stimated by a large amount. The high and low primordial deuterium abun dances imply, respectively, Omega(B)h(2) = 0.005-0.01 and Omega(B)h(2) = O.02-0.03 at 95% C.L. When combined with the high baryon fraction i nferred from x-ray observations of rich clusters, the corresponding to tal mass densities (for 50 less than or equal to H-0 less than or equa l to 90) are Omega(M) = 0.05-0.20 and Omega(M) = 0.2-0.7, respectively (95% C.L.), The range of Omega(M) corresponding to high D is in confl ict with dynamical constraints (Omega(M) greater than or equal to 0.2- 0.3) and with the shape parameter constraint (Gamma = Omega(M)h = 0.25 +/- 0.05) from large scale structure formation in CDM and Lambda CDM models.