Physics Letters B (Jan 2019)

First observation and study of the K± → π±π0e+e− decay

  • J.R. Batley,
  • G. Kalmus,
  • C. Lazzeroni,
  • D.J. Munday,
  • M.W. Slater,
  • S.A. Wotton,
  • R. Arcidiacono,
  • G. Bocquet,
  • N. Cabibbo,
  • A. Ceccucci,
  • D. Cundy,
  • V. Falaleev,
  • M. Fidecaro,
  • L. Gatignon,
  • A. Gonidec,
  • W. Kubischta,
  • A. Maier,
  • A. Norton,
  • M. Patel,
  • A. Peters,
  • S. Balev,
  • P.L. Frabetti,
  • E. Gersabeck,
  • E. Goudzovski,
  • P. Hristov,
  • V. Kekelidze,
  • V. Kozhuharov,
  • L. Litov,
  • D. Madigozhin,
  • M. Misheva,
  • N. Molokanova,
  • I. Polenkevich,
  • Yu. Potrebenikov,
  • S. Stoynev,
  • A. Zinchenko,
  • E. Monnier,
  • E. Swallow,
  • R. Winston,
  • P. Rubin,
  • A. Walker,
  • P. Dalpiaz,
  • C. Damiani,
  • M. Fiorini,
  • M. Martini,
  • F. Petrucci,
  • M. Savrié,
  • M. Scarpa,
  • H. Wahl,
  • W. Baldini,
  • A. Cotta Ramusino,
  • A. Gianoli,
  • M. Calvetti,
  • E. Celeghini,
  • E. Iacopini,
  • M. Lenti,
  • G. Ruggiero,
  • A. Bizzeti,
  • M. Veltri,
  • M. Behler,
  • K. Eppard,
  • M. Hita-Hochgesand,
  • K. Kleinknecht,
  • P. Marouelli,
  • L. Masetti,
  • U. Moosbrugger,
  • C. Morales Morales,
  • B. Renk,
  • M. Wache,
  • R. Wanke,
  • A. Winhart,
  • D. Coward,
  • A. Dabrowski,
  • T. Fonseca Martin,
  • M. Shieh,
  • M. Szleper,
  • M. Velasco,
  • M.D. Wood,
  • G. Anzivino,
  • E. Imbergamo,
  • A. Nappi,
  • M. Piccini,
  • M. Raggi,
  • M. Valdata-Nappi,
  • P. Cenci,
  • M. Pepe,
  • M.C. Petrucci,
  • F. Costantini,
  • N. Doble,
  • L. Fiorini,
  • S. Giudici,
  • G. Pierazzini,
  • M. Sozzi,
  • S. Venditti,
  • G. Collazuol,
  • L. DiLella,
  • G. Lamanna,
  • I. Mannelli,
  • A. Michetti,
  • C. Cerri,
  • R. Fantechi,
  • B. Bloch-Devaux,
  • C. Cheshkov,
  • J.B. Chèze,
  • M. De Beer,
  • J. Derré,
  • G. Marel,
  • E. Mazzucato,
  • B. Peyaud,
  • B. Vallage,
  • M. Holder,
  • M. Ziolkowski,
  • S. Bifani,
  • M. Clemencic,
  • S. Goy Lopez,
  • C. Biino,
  • N. Cartiglia,
  • F. Marchetto,
  • H. Dibon,
  • M. Jeitler,
  • M. Markytan,
  • I. Mikulec,
  • G. Neuhofer,
  • L. Widhalm

Journal volume & issue
Vol. 788
pp. 552 – 561

Abstract

Read online

The NA48/2 experiment at CERN reports the first observation of the K±→π±π0e+e− decay from an exposure of 1.7×1011 charged kaon decays recorded in 2003–2004. A sample of 4919 candidates with 4.9% background contamination allows the determination of the branching ratio in the full kinematic region, BR(K±→π±π0e+e−)=(4.24±0.14)×10−6. The study of the kinematic space shows evidence for a structure dependent contribution in agreement with predictions based on chiral perturbation theory. Several P- and CP-violating asymmetries are also evaluated.