Neutrino mixing as a source for cosmological constant
  We report on recent results showing that neutrino mixing may lead to a non-zero contribution to the cosmological constant. This contribution is of a completely different nature with respect to the usual one by a massive spinor field. We also study the problem of field mixing in Quantum Field Theory in curved space-time, for the case of a scalar field in the Friedmann-Robertson-Walker metric. 
Massimo Blasone, Antonio Capolupo, Salvatore Capozziello, Sante   Carloni and Giuseppe Vitiello