Measurement of the \(\boldsymbol{e}^{\boldsymbol{+}}\boldsymbol{e}^{\boldsymbol{-}}\boldsymbol{\to}{\pi}^{\boldsymbol{+}}{\pi}^{\mathbf{-}}\) Cross Section below 1.2 GeV with the CMD-3 Detector at VEPP-2000 Collider

Abstract

The cross section of the reaction \(e^{+}e^{-}\to\pi^{+}\pi^{-}\) was 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 analyses of the collected data based on the integrated luminosity of about 62 \(\textrm{pb}^{-1}\). The systematic uncertainty of about 0.7\(\%\) has been reached around \(\rho\)-resonance. The forward-backward charge asymmetry for the channel \(\pi^{+}\pi^{-}\) has also been measured. It clear demonstrates the strong deviation from the conventional scalar QED prediction, but it well agrees with [1]. The current results for pion form factor were used to evaluate the hadronic contribution to the anomalous magnetic moment of muon and reveal a discrepancy with the results of previous experiments.