Measurement of sigma(e(+)e(-) -> pi(+)pi(-)gamma(gamma)) and the dipion contribution to the muon anomaly with the KLOE detector

We have measured the cross section sigma(e(+)e(-) -> pi(+)pi(-)gamma(gamma)) at DA Phi NE, the Frascati phi-factory, using events with initial state radiation photons emitted at small angle and inclusive of final state radiation. We present the analysis of a new data set corresponding to an integrated luminosity of 240 pb(-1). We have achieved a reduced systematic uncertainty with respect to previously published KLOE results. From the cross section we obtain the pion form factor and the contribution to the muon magnetic anomaly from two-pion states in the mass range 0.592 < M-pi pi < 0.975 GeV. For the latter we find Delta(pi pi)a(mu) = (387.2 +/- 0.5(stat) +/- 2.4(exp) +/- 2.3(th)) x 10(-10). (C) 2008 Elsevier B.V. All rights reserved.