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 ${}^4\mathrm{He},$ D, and ${}^7\mathrm{Li}.$ The likelihood analysis, based on the Bayesian approach, shows that, in the case of a high deuterium abundance, $Y_D=(2.0\mathrm{}\pm 0.5)\times {10}^{-4},$ both standard and degenerate BBN are inconsistent with the CMBR measurement at more than $3\sigma .$ Assuming a low deuterium abundance, $Y_D=(3.4\mathrm{}\pm 0.3)\times {10}^{-5},$ the standard BBN model is still inconsistent with present observations at the $2\sigma$ 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.