Physics Letters B (Mar 2015)

Study of the Dalitz decay ϕ→ηe+e− with the KLOE detector

  • D. Babusci,
  • I. Balwierz-Pytko,
  • G. Bencivenni,
  • C. Bloise,
  • F. Bossi,
  • P. Branchini,
  • A. Budano,
  • L. Caldeira Balkeståhl,
  • F. Ceradini,
  • P. Ciambrone,
  • F. Curciarello,
  • E. Czerwiński,
  • E. Danè,
  • V. De Leo,
  • E. De Lucia,
  • G. De Robertis,
  • A. De Santis,
  • P. De Simone,
  • A. Di Cicco,
  • A. Di Domenico,
  • R. Di Salvo,
  • D. Domenici,
  • O. Erriquez,
  • G. Fanizzi,
  • A. Fantini,
  • G. Felici,
  • S. Fiore,
  • P. Franzini,
  • A. Gajos,
  • P. Gauzzi,
  • G. Giardina,
  • S. Giovannella,
  • E. Graziani,
  • F. Happacher,
  • L. Heijkenskjöld,
  • B. Höistad,
  • T. Johansson,
  • D. Kamińska,
  • W. Krzemien,
  • A. Kupsc,
  • J. Lee-Franzini,
  • F. Loddo,
  • S. Loffredo,
  • G. Mandaglio,
  • M. Martemianov,
  • M. Martini,
  • M. Mascolo,
  • R. Messi,
  • S. Miscetti,
  • G. Morello,
  • D. Moricciani,
  • P. Moskal,
  • A. Palladino,
  • A. Passeri,
  • V. Patera,
  • I. Prado Longhi,
  • A. Ranieri,
  • P. Santangelo,
  • I. Sarra,
  • M. Schioppa,
  • B. Sciascia,
  • M. Silarski,
  • L. Tortora,
  • G. Venanzoni,
  • W. Wiślicki,
  • M. Wolke

Journal volume & issue
Vol. 742
pp. 1 – 6

Abstract

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We have studied the vector to pseudoscalar conversion decay ϕ→ηe+e−, with η→π0π0π0, with the KLOE detector at DAΦNE. The data set of 1.7 fb−1 of e+e− collisions at s∼Mϕ contains a clear conversion decay signal of ∼31,000 events from which we measured a value of BR(ϕ→ηe+e−)=(1.075±0.007±0.038)×10−4. The same sample is used to determine the transition form factor by a fit to the e+e− invariant mass spectrum, obtaining bϕη=(1.28±0.10−0.08+0.09) GeV−2, that improves by a factor of five the precision of the previous measurement and is in good agreement with VMD expectations. Keywords: e+e− collisions, Conversion decay, Transition form factor