关键词: 缪子反常磁矩, 初态辐射, pion形状因子

Abstract: The precise determination of the e+e-→π+π-(γ) cross section is particularly important to evaluate the hadronic loop contribution to the SM calculation of the muon (g-2), where a long-standing 3σ discrepancy with the direct experimental determination is observed. The KLOE experiment studied the production of π+π- in the ISR channel and published three measurements (in 2005, 2008 and 2012) of the π+π- cross section with the ISR photon emitted at small angles and an independent measurement (in 2010) with the ISR photon emitted at large angles and using data at a collision energy of 1 GeV. The combination of the last analysis (KLOE12) with two previously published (KLOE08, KLOE10) together with the preliminary fit by using the Gounaris-Sakurai model is presented.

Key words: Muon anomaly, Initial state radiation, pion form factor