On the interference betweenC-even andC-odd contributions to the reactione + e − →e + e − π+ π−

We calculate the interference between the bremsstrahlung and the photon-photon collision contributions to the differential cross-section ofe ⁺ e ^? →e ⁺ e ^? π⁺ π^?, for an experiment in which only one electron is tagged. The corresponding pion charge asymmetry has the same order of magnitude as the γγ cross-section in important parts of the phase space.