Measurement of σ(e+e- → π+π-γ) and extraction of σ(e+e- → π+π-) below 1 GeV with the KLOE detector

We have measured the cross section sigma(e(+)e(-) --> pi (+) pi (-) y) at an energy W = m(phi) = 1.02 GeV with the KLOE detector at the electron-positron collider DAPhiNE. From the dependence of the cross section on the invariant mass of the two-pion system, we extract sigma(e(+) e(-) --> pi(+)pi(-)) for the mass range 0.35 < s < 0.95 GeV2. From this result, we calculate the pion form factor and the hadronic contribution to the muon anomaly, A(mu). (C) 2004 Elsevier B.V. All rights reserved.