Published in 1992, "Observational and Physical Cosmology".

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BIG BANG NUCLEOSYNTHESIS AND ABUNDANCES OF LIGHT ELEMENTS

Bernard E.J. Pagel

NORDITA
Blegdamsvej 17
DK-2100 Copenhagen Ø, Denmark


Abstract. Big Bang nucleosynthesis (BBNS) theory is sketched, indicating the dependence of primordial abundances of D, 3He, 4He and 7Li on the mean baryonic density of the universe and the dependence of 4He on the number of neutrino families and the neutron half-life. Observational data and inferred primordial abundances of these elements are reviewed and shown to be consistent (within errors) either with standard BBNS in a homogeneous universe about 100 seconds after the Big Bang or with moderately inhomogeneous BBNS models resulting from earlier phase transitions like the quark-hadron transition if this is first order. However, models with closure density supplied by baryons are apparently ruled out. Finally, implications for the existence of baryonic and non-baryonic dark matter are briefly discussed.


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