Testing standard and degenerate big bang nucleosynthesis with BOOMERANG and MAXIMA-1

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 the Bayesian approach, shows that, in the case of a high deuterium abundance, Y₃= (2. 00. 5) 10^-4, both standard and degenerate BBN are inconsistent with the CMBR measurement at more than 3. Assuming a low deuterium abundance, Y₃= (3. 40. 3) 10^-5, the standard BBN model is still inconsistent with present observations at the 2 level, while 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 favor of new physics such as a large chemical potential of the relic neutrino-antineutrino background.