MEASUREMENT OF THE HADRONIC CROSS SECTION VIA RADIATIVE RETURN AT DAΦNE

The cross section σ(e+e-→π+π-γ) has been measured with the KLOE detector at the electron-positron collider DAΦNE, at an energy W=mϕ=1.02 GeV . We perform this measurement as a function of the π+π- invariant mass, Mππ. The photon in the above process is due to Initial State Radiation. Dividing by a theoretical radiator function, we obtain the cross section σ(e+e-→π+π-) for the mass range [Formula: see text] with an overall accuracy of 1.3%. We also calculate the hadronic contribution of the two-pion channel to the anomalous magnetic moment of the muon for the given mass range: [Formula: see text].