Precise measurement of the K ± → π ± e + e - decay

J. R. Batley, A. J. Culling, 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. Norton, A. Maier, M. PatelA. Peters, S. Balev, P. L. Frabetti, E. Goudzovski*, P. Hristov, V. Kekelidze, V. Kozhuharov, L. Litov, D. Madigozhin, E. Marinova, N. Molokanova, I. Polenkevich, Yu Potrebenikov, S. Stoynev, A. Zinchenko, E. Monnier, E. Swallow, R. Winston, P. Rubin, A. Walker, W. Baldini, A. Cotta Ramusino, P. Dalpiaz, C. Damiani, M. Fiorini, A. Gianoli, M. Martini, F. Petrucci, M. Savrié, M. Scarpa, H. Wahl, A. Bizzeti, M. Calvetti, E. Celeghini, E. Iacopini, M. Lenti, F. Martelli, G. Ruggiero, M. Veltri, M. Behler, K. Eppard, 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, P. Cenci, E. Imbergamo, A. Nappi, M. Pepe, M. C. Petrucci, M. Piccini, M. Raggi, M. Valdata-Nappi, C. Cerri, R. Fantechi, G. Collazuol, L. DiLella, G. Lamanna, I. Mannelli, A. Michetti, F. Costantini, N. Doble, L. Fiorini, S. Giudici, G. Pierazzini, M. Sozzi, S. Venditti, 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, C. Biino, N. Cartiglia, M. Clemencic, S. Goy Lopez, F. Marchetto, H. Dibon, M. Jeitler, M. Markytan, I. Mikulec, G. Neuhofer, L. Widhalm

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

65 Scopus citations

Abstract

A sample of 7253 K ± → π ± e + e - (γ) decay candidates with 1.0% background contamination has been collected by the NA48/2 experiment at the CERN SPS, which allowed a precise measurement of the decay properties. The branching ratio in the full kinematic range was measured to be BR = (3.11 ± 0.12) × 10 - 7, where the uncertainty includes also the model dependence. The shape of the form factor W (z), where z = (M e e / M K) 2, was parameterized according to several models, and, in particular, the slope δ of the linear form factor W (z) = W 0 (1 + δ z) was determined to be δ = 2.32 ± 0.18. A possible CP violating asymmetry of K + and K - decay widths was investigated, and a conservative upper limit of 2.1 × 10 - 2 at 90% CL was established.

Original languageEnglish (US)
Pages (from-to)246-254
Number of pages9
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Volume677
Issue number5
DOIs
StatePublished - Jun 29 2009

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

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