An exactly solvable Quantum Field Theory (QFT) model of Lee-type is
constructed to study how neutrino flavor eigenstates are created through
interactions and how the localization properties of neutrinos follows from the
parent particle that decays. The two-particle states formed by the neutrino and
the accompanying charged lepton can be calculated exactly as well as their
creation probabilities. We can show that the coherent creation of neutrino
flavor eigenstates follows from the common negligible contribution of neutrino
masses to their creation probabilities. On the other hand, it is shown that it
is not possible to associate a well defined "flavor" to mixed states of charged
leptons.Comment: v2: 25pp in preprint form, typos corrected and references added, one
paragraph around Eq.(90) added in conclusion