Accessing the Final-State Interactions in the Semi-inclusive Two-Pion Annihilation at the Future Tau-Charm Factory

Measuring the single spin asymmetry for the inclusive almost back-to-back two-pion production by electron-positron annihilation to access the corresponding final-state interactions is suggested. Such an experiment will be a spin-off of the future high luminosity Tau-Charm Factory. On the basis of the positivity of the photon fragmentation tensor, an upper bound is derived to the single spin asymmetry suggested.