The hadronic invariant mass distribution for the process of electron--positron annihilation into a pair of charged pions accompanied by a photon radiated from the initial state has been studied for the region of DAΦNE energies. The Born cross--section and the electromagnetic radiative corrections to it are calculated for realistic conditions of the KLOE detector. The dependence on the physical parameters which define the event selection is obtained.
V.A. et al. (Thu,) studied this question.