The quantum field theory of fermion mixing
Journal of Physics A: Mathematical and General
Blasone and Vitiello showed that for two or three flavours the mass and flavour vacua for fermion mixing define inequivalent representations of the anticommutation relations. This paper presents a short proof that this holds for any number of flavours and momentum-dependent mixing, and also extends the Blasone-Vitiello formulae for the oscillations.
K, C H, and C L. D. "The Quantum Field Theory of Fermion Mixing." Journal of Physics A: Mathematical and General. 33.7 (2000): 1369-1373. Print.