Decaying neutrino and a high cosmological baryon density
  The low second acoustic peak in the recent Boomerang data may indicate a cosmological baryon density which is larger than allowed by standard big bang nucleosynthesis.   We show that the decay of the tau-neutrino: nu_tau -> nu_e + phi, where nu_e is the electron neutrino and phi is a scalar, essentially can assure agreement between BBN calculations and light element observations for a large baryon density. 
S.H. Hansen and F.L. Villante