Measurement of $\sigma (e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-})$ at DA$\Phi$NE with the radiative return

Abstract

The measurement of hadronic cross sections at low centre-of-mass energies is currently attracting much interest because of the rô{}le these measurements play in the theoretical evaluation of the anomalous magnetic moment of the muon. The KLOE experiment at the DA$\Phi$NE $\varphi$-factory in Frascati aims to determine the cross section of the dominant contribution $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}$ at energies below 1 GeV exploiting the radiative return from the $\varphi$ to the $\rho$ and $\omega$ mesons. This method has systematic errors completely different from previous measurements and allows a cross check of existing data in this energy region. The method and results on both the differential cross section for $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}\gamma$ and the total cross section for $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}$ are presented.

arXiv comment6 pages, 5 figures, Invited talk at the Workshop on e+e- in the 1-2 GeV range, Alghero, Italy, September 2003 (eConf C0309101); References completed, pdf-visibility improved