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arXiv · 1006.5313

Measurement of sigma(e+ e- -> pi+ pi-) from threshold to 0.85 GeV^2 using Initial State Radiation with the KLOE detector

KLOE Collaboration·F. Ambrosino·F. Archilli·P. Beltrame·G. Bencivenni·C. Bini·C. Bloise·S. Bocchetta·F. Bossi·P. Branchini·G. Capon·T. Capussela·F. Ceradini·P. Ciambrone·E. De Lucia·A. De Santis·P. De Simone·G. De Zorzi·A. Denig·A. Di Domenico·C. Di Donato·B. Di Micco·M. Dreucci·G. Felici·S. Fiore·P. Franzini·C. Gatti·P. Gauzzi·S. Giovannella·E. Graziani·M. Jacewicz·W. Kluge·J. Lee-Franzini·D. Leone·P. Massarotti·S. Meola·S. Miscetti·S. Müller·F. Murtas·M. Napolitano·F. Nguyen·A. Passeri·V. Patera·P. Santangelo·C. Taccini·L. Tortora·G. Venanzoni·R. Versaci
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Abstract

We have measured the cross section of the radiative process e+e- -> pi+pi-gamma with the KLOE detector at the Frascati phi-factory DAPHNE, from events taken at a CM energy W=1 GeV. Initial state radiation allows us to obtain the cross section for e+e- -> pi+pi-, the pion form factor |F_pi|^2 and the dipion contribution to the muon magnetic moment anomaly, Delta a_mu^{pipi} = (478.5+-2.0_{stat}+-5.0_{syst}+-4.5_{th}) x 10^{-10} in the range 0.1 < M_{pipi}^2 < 0.85 GeV^2, where the theoretical error includes a SU(3) ChPT estimate of the uncertainty on photon radiation from the final pions. The discrepancy between the Standard Model evaluation of a_mu and the value measured by the Muon g-2 collaboration at BNL is confirmed.

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KLOE Collaboration, F. Ambrosino, F. Archilli, P. Beltrame, G. Bencivenni, C. Bini, C. Bloise, S. Bocchetta, F. Bossi, P. Branchini, G. Capon, T. Capussela, F. Ceradini, P. Ciambrone, E. De Lucia, A. De Santis, P. De Simone, G. De Zorzi, A. Denig, A. Di Domenico, C. Di Donato, B. Di Micco, M. Dreucci, G. Felici, S. Fiore, P. Franzini, C. Gatti, P. Gauzzi, S. Giovannella, E. Graziani, M. Jacewicz, W. Kluge, J. Lee-Franzini, D. Leone, P. Massarotti, S. Meola, S. Miscetti, S. Müller, F. Murtas, M. Napolitano, F. Nguyen, A. Passeri, V. Patera, P. Santangelo, C. Taccini, L. Tortora, G. Venanzoni, R. Versaci. 2011-05-21. Measurement of sigma(e+ e- -> pi+ pi-) from threshold to 0.85 GeV^2 using Initial State Radiation with the KLOE detector. https://doi.org/10.1016/j.physletb.2011.04.055

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