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The WMAP satellite, devoted to the observations of the anisotropies of theCosmic Microwave Background (CMB) radiation, has recently provided adetermination of the baryonic density of the Universe with unprecedentedprecision. Using this, Big Bang Nucleosynthesis (BBN) calculations predict aprimordial 7Li abundance which is a factor 2-3 higher than that observed ingalactic halo dwarf stars. It has been argued that this discrepancy could beresolved if the 7Be(d,p)2alpha reaction rate is around a factor of 100 largerthan has previously been considered. We have now studied this reaction, for thefirst time at energies appropriate to the Big Bang environment, at the CYCLONEradioactive beam facility at Louvain-la-Neuve. The cross section was found tobe a factor of 10 smaller than derived from earlier measurements. It isconcluded therefore that nuclear uncertainties cannot explain the discrepancybetween observed and predicted primordial 7Li abundances, and an alternativeastrophysical solution must be investigated.Comment: To appear in Astrophysical J. Letter

The 7 Be( d , p )2α Cross Section at Big Bang Energies and the Primordial 7 Li Abundance

The ⁷ Be( d , p )2α Cross Section at Big Bang Energies and the Primordial ⁷ Li Abundance