Measuring the Hadronic Cross Section at KLOE using the Radiative Return

Abstract

We present a study of the reaction e+e- \to pi+pi-gamma at the phi peak with the KLOE detector at the phi-factory DAPHNE. This reaction allows us to obtain the cross section for \e+e- \to pi+pi- from the e+e- center-of-mass energy W = m_ϕ= 1019 MeV down to threshold, i.e. 2m_pi < M_(pipi) < m_phi. This is called radiative return. The status of the analysis and preliminary results on the invariant mass spectrum of the two-pion-state are presented.

Contributed Paper to "Lepton Photon 2001" Conference, Rome, July 23-28 2001; 7 pages, 5 plots