On the role of the rotations and Bogoliubov transformations in neutrino   mixing
  We show that mixing transformations for Dirac fields arise as a consequence of the non-trivial interplay between rotations and Bogoliubov transformations at level of ladder operators. Indeed the non-commutativity between the algebraic generators of such transformations turns out to be responsible of the unitary inequivalence of the flavor and mass representations and of the associated vacuum structure. A possible thermodynamic interpretation is also investigated. 
Massimo Blasone, Maria Vittoria Gargiulo and Giuseppe Vitiello
hep-th