Model-independent description of C- and CP-violation in η decays

We present a model-independent, non-perturbative construction of the hadronic amplitudes η→π⁺π^– π⁰ and η'→ηπ⁺π^–, allowing for C- and CP-violating asymmetries in the π⁺π^– distributions. These amplitudes are consistent with the constraints of analyticity and unitarity. Our dispersive representation allows us to extract the individual coupling strengths of the C- and CP-violating contributions arising from effective isoscalar and isotensor operators in η→π⁺π^– π⁰ and an effective isovector operator in η'→ηπ⁺π^–. We furthermore discuss the possibility of deriving C- and CP-odd η decays in a model-independent manner from effective field theories.