Measuring the Pion From Factor via Radiative Return at large photon angles with KLOE

The KLOE experiment at the electron-positron collider DAΦNE uses the radiative return to measure the hadronic cross section σ(e+e−→π+π−). The energy of DAΦNE is fixed at , but the emission of one (or more) photons in the initial state (ISR) reduces the collision energy, allowing to cover the two-pion invariant mass Mππ in the region from the two pion threshold to mϕ. The precise measurement of this cross section is used to calculate the hadronic contribution to the muon anomaly aμ. A first measurement, in which the ISR-photon is detected at small polar angles, has already been performed at KLOE. Here we present the status of a complementary analysis at large photon polar angles. This allows to extend the measurement of the two-pion cross section to low masses below 600 MeV.