Precision measurement of the hadronic contribution to the muon anomalous magnetic moment

We report on a precision measurement of the cross section for the reaction e+e-→π+π- in the mass range 0.30<Mππ<1.00 GeV/c2 with the initial state radiation (ISR) method, using 817 pb-1 of data at e+e- center-of-mass energies near 3.77 GeV and 586 pb-1 of data at e+e- center-of-mass energies near 4.17 GeV, collected with the CLEO-c detector at the CESR e+e- collider at Cornell University. The integrated cross sections in the range 0.30<Mππ<1.00 GeV/c2 for the process e+e-→π+π- are determined with a statistical uncertainty of 0.7% and a systematic uncertainty of 1.6%. The leading-order hadronic contribution to the muon anomalous magnetic moment calculated using these measured e+e-→π+π- cross sections in the range Mππ=0.30 to 1.00 GeV/c2 is calculated to be (500.6±3.6(stat)±8.0(syst))×10-10.