1. First observation and study of the K± → π±π0e+e− decay
- Author
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Batley, J. R., Kalmus, G., Lazzeroni, C., Munday, D. J., Slater, M. W., Wotton, S. A., Arcidiacono, R., Bocquet, G., Cabibbo, N., Ceccucci, A., Cundy, D., Bloch-Devaux, B., Cheshkov, C., Cheze, J. B., De Beer, M., Derre, J., Marel, G., Mazzucato, E., Peyaud, B., Vallage, B., Holder, M., Falaleev, V., Ziolkowski, M., Bifani, S., Clemencic, M., Lopez, S. Goy, Biino, C., Cartiglia, N., Marchetto, F., Dibon, H., Jeitler, M., Markytan, M., Fidecaro, M., Mikulec, I., Neuhofer, G., Widhalm, L., NA48/2 Collaboration, Gatignon, L., Gonidec, A., Kubischta, W., Maier, A., Norton, A., Patel, M., Peters, A., Balev, S., Frabetti, P. L., Gersabeck, E., Goudzovski, E., Hristov, P., Kekelidze, V., Kozhuharov, V., Litov, L., Madigozhin, D., Misheva, M., Molokanova, N., Polenkevich, I., Potrebenikov, Yu., Stoynev, S., Zinchenko, A., Monnier, E., Swallow, E., Winston, R., Rubin, P., Walker, A., Dalpiaz, P., Damiani, C., Fiorini, M., Martini, M., Petrucci, F., Savrie, M., Scarpa, M., Wahl, H., Baldini, W., Ramusino, A. Cotta, Gianoli, A., Calvetti, M., Celeghini, E., Iacopini, E., Lenti, M., Ruggiero, G., Bizzeti, A., Veltri, M., Behler, M., Eppard, K., Hita-Hochgesand, M., Kleinknecht, K., Marouelli, P., Masetti, L., Moosbrugger, U., MoralesMorales, C., Renk, B., Wache, M., Wanke, R., Winhart, A., Coward, D., Dabrowski, A., Fonseca Martin, T., Shieh, M., Szleper, M., Velasco, M., Wood, M. D., Anzivino, G., Imbergamo, E., Nappi, A., Piccini, M., Raggi, M., Valdata-Nappi, M., Cenci, P., Pepe, M., Petrucci, M. C., Costantini, F., Doble, N., Fiorini, L., Giudici, S., Pierazzini, G., Sozzi, M., Venditti, S., Collazuol, G., DiLella, L., Lamanna, G., Mannelli, I., Michetti, A., Cerri, C., and Fantechi, R.
- Subjects
rare decay ,Nuclear and High Energy Physics ,Chiral perturbation theory ,CP violation ,Monte-Carlo ,search ,Astronomy & Astrophysics ,Space (mathematics) ,quark mixing ,01 natural sciences ,Partícules (Física nuclear) ,Charged Kaon decays ,Physics, Particles & Fields ,Charged Kaon decays, quark mixing, radiative kaon decay, chiral perturbation theory ,Economica ,0202 Atomic, Molecular, Nuclear, Particle And Plasma Physics ,Violació CP (Física nuclear) ,MONTE-CARLO ,SEARCH ,0103 physical sciences ,Kaon decays ,radiative kaon decay ,010306 general physics ,Physics ,Science & Technology ,010308 nuclear & particles physics ,Branching fraction ,Kaon decays, Chiral Perturbation Theory ,Ambientale ,K meson ,Nuclear & Particles Physics ,Chiral Perturbation Theory ,lcsh:QC1-999 ,fixed target experiment ,Physics, Nuclear ,Physical Sciences ,K meson, rare decay, fixed target experiment ,High Energy Physics::Experiment ,CP VIOLATION ,Atomic physics ,lcsh:Physics - Abstract
The NA48/2 experiment at CERN reports the first observation of the K-+/- -> pi(+/-)pi(0)e(+)e(-) decay from an exposure of 1.7 x 10(11) 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-+/- -> pi(+/-)pi(0)e(+)e(-)) = (4.24 +/- 0.14) x 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., We gratefully acknowledge the CERN SPS accelerator and beam line staff for the excellent performance of the beam and the technical staff of the participating institutes for their efforts in the maintenance and operation of the detector, and data processing. We thank M. Koval for making the “Prague” radiative Dalitz decay code available in the NA48/2 simulation software. Discussions with G. D'Ambrosio and O. Catà were most stimulating in clarifying the impact of interference terms on our measurement.
- Published
- 2019