The reaction e+e−→e+e−π+π− and the pion form factor measurements via the radiative return method

The role of the reaction e+e−→e+e−π+π− in the pion form factor measurements via the radiative return method without photon tagging is studied in detail. It was shown, that for the KLOE event selection, it gives up to 1% contribution to the reaction e+e−→π+π−γ(γ) for low invariant masses of the two-pion system.