Measurement of the Hadronic Cross Section at DaΦne with the KLOE Detector

Abstract

We have measured the cross section σ(e+e− → π+π−γ) as a function of the π+π− invariant mass, Mππ, with the KLOE detector at DAΦNE ( W = mφ = 1.02 GeV ). 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 0.37 < Mππ2 < 0.93 GeV2. We extract the pion form factor and the hadronic contribution to the muon anomaly, a μ.