Casimir effect for mixed fields

We analyze the Casimir effect for a flavor doublet of mixed scalar fields confined inside a one-dimensional finite region. In the framework of the unitary inequivalence between mass and flavor representations in quantum field theory, we employ two alternative approaches to derive the Casimir force: in the first case, the zero-point energy is evaluated for the vacuum of fields with definite mass, then similar calculations are performed for the vacuum of fields with definite flavor. We find that signatures of mixing only appear in the latter context, showing the result to be independent of the mixing parameters in the former.