Measurement of the e+e- --> hadrons cross-section at low energy with ISR events at BABAR

Abstract

The precise measurement of the cross section e+e- --> pi+ pi-(gamma) from threshold to an energy of 3 GeV, using events with Initial State Radiation (ISR) collected with the BABAR detector, is presented. The ISR luminosity is determined from a study of the leptonic process e+e- --> mu+ mu- gamma(gamma), and the method is tested by the comparison with the next-to-leading order (NLO) QED prediction. The leading-order hadronic contribution to the muon magnetic anomaly calculated using the BABAR pi pi cross section measured from threshold to 1.8 GeV is (514.1 +- 2.2(stat) +- 3.1(syst)) * 10^{-10}. Other results on ISR multihadronic cross sections from BABAR are presented.

On behalf of the BABAR Collaboration. Proceeding of the 11th International Workshop on Tau Lepton Physics - Manchester, UK, 13-17 September 2010. 6 pages, 3 figures

References in corpus (4)

• Precise measurement of the e+ e- to pi+ pi- (gamma) cross section with the Initial State Radiation method at BABAR
• Update of the e^+e^-\toπ^+π^- cross section measured by SND detector in the energy region 400<\sqrt{s}<1000 MeV
• Reevaluation of the hadronic contribution to the muon magnetic anomaly using new e+e- -> pi+pi- cross section data from BABAR
• The Discrepancy Between tau and e+e- Spectral Functions Revisited and the Consequences for the Muon Magnetic Anomaly