CMD-3 Collab.
Measurement of the e+e−→π+π− cross section from threshold to 1.2 GeV
with the CMD-3 detector
The cross section of the process e+e−→π+π− has been measured in the center of mass energy range from 0.32 to 1.2 GeV with the CMD-3 detector at the electron-positron collider VEPP-2000. The measurement is based on a full dataset collected below 1 GeV during three data taking seasons, corresponding to an integrated luminosity of about 62 pb−1. In the dominant ρ-resonance region, a systematic uncertainty of 0.7 % has been reached. At energies around ϕ-resonance the π+π− production cross section was measured for the first time with high energy resolution. The forward-backward charge asymmetry in the π+π− production has also been measured. It shows the strong deviation from the theoretical prediction based on conventional sQED framework and is in good agreement with GVDM and dispersive-based predictions. The impact of presented results on the evaluation of the hadronic contribution to the anomalous magnetic moment of muon is discussed.