| Popis: |
The measurement of the ratio σ(e+e− → π+π−γ)/σ(e+e− → μ+μ−γ) was performed with the KLOE detector at DAΦNE, the Frascati ϕ-factory, using events with initial state radiation photons emitted at small angle and inclusive of the final state radiation. The analysis is based on a data set corresponding to an integrated luminosity of 240 pb−1. The cross section σ(e+e− → π+π−), obtained from the ratio, has been used to determine the pion form factor |Fπ|2 and the two pion contribution to the muon anomaly aμ for 0.592 < Mππ < 0.975GeV. The result confirms the previous KLOE measurements and the current discrepancy between the Standard Model calculation and the experimental value of the muon anomaly. The preliminary results on the combination of the last analysis (KLOE12) with the previous published (KLOE08,KLOE10) will be also presented. |
