Precise measurement of the e+e- → π+π- (γ) cross section with the initial state radiation method at BABAR

Abstract

We present a precise BABAR measurement on the cross section of the process e+e- → π+π- (γ) from threshold to an energy of 3 GeV with the initial state radiation (ISR) technique, using 232 fb-1 of data collected with the BABAR detector at e+e- center-of-mass energies near 10.58 GeV. The ISR luminosity is determined from a study of the leptonic process e +e- → μ+μ -γ(γ). The leading-order hadronic contribution to the muon magnetic anomaly calculated using the ππ cross section measured from threshold to 1.8 GeV is (514.1±2.2(stat)±3.1(syst)) × 10-10. © 2010 Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Sciences and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd.