Precision measurement of the ratio BR(KS→π+π-e+e-)/BR(KL→π+π-πD0)

J. R. Batley, G. E. Kalmus, C. Lazzeroni, D. J. Munday, M. Patel, M. W. Slater, S. A. Wotton, R. Arcidiacono, G. Bocquet, A. Ceccucci, D. Cundy, N. Doble, V. Falaleev, L. Gatignon, A. Gonidec, P. Grafström, W. Kubischta, F. Marchetto, I. Mikulec, A. NortonB. Panzer-Steindel, P. Rubin, H. Wahl, E. Goudzovski, P. Hristov, V. Kekelidze, V. Kozhuharov, L. Litov, D. Madigozhin, N. Molokanova, Y. Potrebenikov, S. Stoynev, A. Zinchenko, E. Monnier, E. C. Swallow, R. Winston, R. Sacco, A. Walker, W. Baldini, P. Dalpiaz, P. L. Frabetti, A. Gianoli, M. Martini, F. Petrucci, M. Savrié, M. Scarpa, M. Calvetti, G. Collazuol, E. Iacopini, G. Ruggiero, A. Bizzeti, M. Lenti, M. Veltri, M. Behler, K. Eppard, M. Eppard, A. Hirstius, K. Kleinknecht, U. Koch, P. Marouelli, L. Masetti, U. Moosbrugger, C. Morales Morales, A. Peters, R. Wanke, A. Winhart, A. Dabrowski, T. Fonseca Martin, M. Szleper, Mayda Velasco, G. Anzivino, E. Imbergamo, G. Lamanna, P. Lubrano, A. Michetti, A. Nappi, M. Piccini, M. Valdata-Nappi, P. Cenci, M. Pepe, M. C. Petrucci, C. Cerri, R. Fantechi, I. Mannelli, F. Costantini, L. Fiorini, S. Giudici, G. Pierazzini, M. Sozzi, C. Cheshkov, J. B. Chèze, M. De Beer, P. Debu, G. Gouge, G. Marel, E. Mazzucato*, B. Peyaud, B. Vallage, M. Holder, A. Maier, M. Ziolkowski, C. Biino, N. Cartiglia, M. Clemencic, S. Goy Lopez, E. Menichetti, N. Pastrone, W. Wislicki, H. Dibon, M. Jeitler, M. Markytan, G. Neuhofer, L. Widhalm

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


The KS→π+π-e+e- decay mode was investigated using the data collected in 2002 by the NA48/1 Collaboration. With about 23 k KS→π+π-e+e- events and 59 k KL→π+π-πD0 normalization decays, the KS→π+π-e+e- branching ratio relative to the KL→π+π-πD0 one was determined to be BR(KS→π+π-e+e-)/BR(KL→π+π-πD0)=(3.28±0.06stat±0.04syst)×10-2. This result was used to set the upper limit |gE1/gBR|<3.0 at 90% CL on the presence, in the decay amplitude, of an E1 direct emission (gE1) term relative to the dominant inner bremsstrahlung (gBR) term. The CP-violating asymmetry Aø in the sinøcosø distribution of KS→π+π-e+e- events, where ø is the angle between the π+π- and the e+e- decay planes in the kaon centre of mass, was found to be Aø=(-0.4±0.8)%, consistent with zero. These results are in good agreement with a description of the KS→π+π-e+e- decay amplitude dominated by the CP-even inner bremsstrahlung process.

Original languageEnglish (US)
Pages (from-to)301-309
Number of pages9
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Issue number4-5
StatePublished - Jan 3 2011


  • CP-violating asymmetry
  • Direct emission
  • Inner bremsstrahlung
  • Kaon rare decay
  • Neutral kaon radiative decay

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


Dive into the research topics of 'Precision measurement of the ratio BR(KS→π+π-e+e-)/BR(KL→π+π-πD0)'. Together they form a unique fingerprint.

Cite this