Testing standard and degenerate big bang nucleosynthesis with BOOMERANG and MAXIMA-1 - art. no. 043004

We test different big bang nucleosynthesis scenarios using the recent resul ts on the cosmic microwave background anisotropies provided by the BOOMERAN G and MAXIMA-1 experiments versus the observed abundances of He-4, D, and L i-7. The Likelihood analysis, based on the Bayesian approach, shows that, i n the case of a high deuterium abundance, Y-D = (2.0 +/- 0.5) X 10(-4), bot h standard and degenerate BBN are inconsistent with the CMBR measurement at more than 3 sigma. Assuming a low deuterium abundance, Y-D = (3.4 +/- 0.3) X 10(-5), the standard BBN model is still inconsistent with present observ ations at the 2 sigma level, while degenerate BBN results to be compatible. Unless systematics effects will be found in nuclide abundances and/or in C MBR data analysis this result may be a signal in favor of new physics such as a large chemical potential of the relic neutrino-antineutrino background .