High accuracy description of radiative return production of low-mass muon and pion pairs at $e^+e^-$-colliders

The process of muon (pion) pair production with small invariant mass in electron-positron high-energy annihilation, accompanied by emission of a hard photon at large angles, is considered. We find that the Drell–Yan picture for the differential cross section is valid in the charge-even experimental set-up. Radiative corrections both for the electron block and for the final state block are taken into account.