0 ) with the KLOE Detector The KLOE / KLOE-2 Collaboration
D. Babusci,D. Badoni,I. Balwierz-Pytko,G. Bencivenni,C. Bini,C. Bloise,V. Bocci,F. Bossi,P. Branchini,A. Budano,L. Caldeira Balkest̊ahl,G. Capon,F. Ceradini,P. Ciambrone,E. Czerwiński,E. Dané,E. De Lucia,G. De Robertis,A. De Santis,P. De Simone,A. Di Domenico,C. Di Donato,B. Di Micco,R. Di Salvo,D. Domenici,O. Erriquez,G. Fanizzi,A. Fantini,G. Felici,S. Fiore,P. Franzini,P. Gauzzi,G. Giardina,S. Giovannella,F. Gonnella,E. Graziani,F. Happacher,B. Höistad,L. Iafolla,M. Jacewicz,T. Johansson,A. Kupsc,J. Lee-Franzini,B. Leverington,F. Loddo,S. Loffredo,G. Mandaglio,M. Martemianov,M. Martini,M. Mascolo,R. Messi,S. Miscetti,G. Morello,D. Moricciani,P. Moskal,F. Nguyen,A. Passeri,V. Patera,I. Prado Longhi,A. Ranieri,C. F. Redmer,P. Santangelo,I. Sarra,M. Schioppa,B. Sciascia,M. Silarski,C. Taccini,L. Tortora,G. Venanzoni,R. Versaci,W. Wíslicki
semanticscholar（2013）
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摘要
The ratio Rη = Γ(η → π+π−γ)/Γ(η → π+π−π0) has been measured by analysing 22 million φ → ηγ decays collected by the KLOE experiment at DAΦNE, corresponding to an integrated luminosity of 558 pb−1. The η → π+π−γ proceeds both via the ρ resonant contribution, and possibly a non-resonant direct term, connected to the box anomaly. Our result, Rη = 0.1856 ± 0.0005stat ± 0.0028syst, points out a sizable contribution of the direct term to the total width. The di-pion invariant mass for the η → π+π−γ decay could be described in a model-independent approach in terms of a single free parameter, α. The determined value of the parameter α is α = (1.32 ± 0.08stat −0.09syst±0.02theo) GeV−2.
