Quantum field theory of meson mixing

We develop a quantum-field-theoretic framework for scalar and pseudoscalar meson mixing and oscillations in time. The unitary inequivalence of the Fock space of base (unmixed) eigenstates and the physical mixed eigenstates is proven and shown to lead to a rich condensate structure. This is exploited to develop formulas for two-flavor boson oscillations in systems of arbitrary boson occupation number. The mixing and oscillation can be understood in terms of a vacuum condensate which interacts with the bare particles to induce nontrivial effects. We apply these formulas to analyze the mixing of η with η' and comment on the KLKS system. In addition, we consider the mixing of boson coherent states, which may have future applications in the construction of meson lasers. copyright 1999 The American Physical Society