Measurement of σ(e+e−→π+π−γ(γ)) and the dipion contribution to the muon anomaly with the KLOE detector

• DOI: 10.1016/j.physletb.2008.10.060
• Publication Date: 2008-11-09T09:56:31Z
• Authors: F. Ambrosino; A. Antonelli; M. Antonelli; F. Archilli; C. Bacci; P. Beltrame; G. Bencivenni; S. Bertolucci; C. Bini; C. Bloise; S. Bocchetta; F. Bossi; P. Branchini; P. Campana; G. Capon; T. Capussela; F. Ceradini; S. Chi; G. Chiefari; P. Ciambrone; F. Crucianelli; E. De Lucia; A. De Santis; P. De Simone; G. De Zorzi; A. Denig; A. Di Domenico; C. Di Donato; S. Di Falco; B. Di Micco; A. Doria; M. Dreucci; G. Felici; A. Ferrari; M.L. Ferrer; S. Fiore; C. Forti; P. Franzini; C. Gatti; P. Gauzzi; S. Giovannella; E. Gorini; E. Graziani; M. Incagli; W. Kluge; V. Kulikov; F. Lacava; G. Lanfranchi; J. Lee-Franzini; D. Leone; M. Martemianov; M. Martini; P. Massarotti; W. Mei; S. Meola; S. Miscetti; M. Moulson; S. Müller; F. Murtas; M. Napolitano; F. Nguyen; M. Palutan; E. Pasqualucci; A. Passeri; V. Patera; F. Perfetto; M. Primavera; P. Santangelo; G. Saracino; B. Sciascia; A. Sciubba; A. Sibidanov; T. Spadaro; M. Testa; L. Tortora; P. Valente; B. Valeriani; G. Venanzoni; R. Versaci; G. Xu
• Keywords: 0103 physical sciences; 01 natural sciences; 7. Clean energy

Abstract We have measured the cross section σ ( e + e − → π + π − γ ( γ ) ) at DAΦNE, the Frascati ϕ-factory, using events with initial state radiation photons emitted at small angle and inclusive of final state radiation. We present the analysis of a new data set corresponding to an integrated luminosity of 240 pb−1. We have achieved a reduced systematic uncertainty with respect to previously published KLOE results. From the cross section we obtain the pion form factor and the contribution to the muon magnetic anomaly from two-pion states in the mass range 0.592 M π π 0.975 GeV . For the latter we find Δ π π a μ = ( 387.2 ± 0.5 stat ± 2.4 exp ± 2.3 th ) × 10 −10 .