Testing Standard and Degenerate Big Bang Nucleosynthesis with BOOMERanG and MAXIMA-1

Abstract

We test different Big Bang Nucleosynthesis scenarios using the recent results on the Cosmic Microwave Background Anisotropies provided by the BOOMERanG and MAXIMA-1 experiments versus the observed abundances of 4He, D and 7Li. The likelihood analysis, based on Bayesian approach, shows that, in the case of high deuterium abundance, Y_D=(2.0\pm0.5) 10^{-4}, both standard and degenerate BBN are inconsistent with the CMBR measurement at more than 3 σ. Assuming low deuterium abundance, Y_D=(3.4\pm0.3) 10^{-5}, the standard BBN model is still inconsistent with present observations at 2 σlevel, while the degenerate BBN results to be compatible. Unless systematics effects will be found in nuclide abundances and/or in CMBR data analysis this result may be a signal in favour of new physics like a large chemical potential of the relic neutrino-antineutrino background.

4 pages, RevTeX, 2 figures .eps. Some typos corrected, figure 1 improved