Phenomenology of flavor oscillations with non-perturbative effects from   quantum field theory
  We analyze phenomenological aspects of the quantum field theoretical formulation of meson mixing and obtain the exact oscillation formula in the presence of the decay. This formula is different from quantum mechanical formula by additional high-frequency oscillation terms. In the infinite volume limit, the space of the flavor quantum states is unitarily inequivalent to the space of energy eigenstates. 
Antonio Capolupo, Chueng-Ryong Ji, Yuriy Mishchenko, Giuseppe Vitiello