Primordial nucleosynthesis and chemical evolution of galaxies

Simple or canonical Big Bang models are claimed to account properly for the abundances of the lightest elements D, 3He, 4He and 7Li if the baryonic cosmological parameter of the Universe is ΩB < 0.1 and if the maximum number of neutrino families is 3. Agreement between the predictions of such models and the primordial abundances deduced from observations is not as compelling or striking as the proponents of such a simple (and therefore beautiful) hypothesis would like. In order to reconcile these simple models with the observations we argue that the galactic evolution should be such that a significant fraction of D has to be destroyed during the history of the Galaxy. As a consequence the resulting ΩB is lower than 0.06 i.e. significantly smaller than in the simplest framework. Moreover this hypothesis of significant D destruction during the galactic evolution could be observationally tested