First observation and study of the K ± → π ± π 0 e + e − decay

Batley, J. R. and Kalmus, G. and Lazzeroni, C. and Slater, M. W. and Wotton, S. A. and Arcidiacono, R. and Bocquet, G. and Cabibbo, N. and Ceccucci, A. and Cundy, D. and Falaleev, V. and Fidecaro, M. and Gatignon, L. and Gonidec, A. and Kubischta, W. and Maier, A. and Norton, A. and Patel, M. and Balev, S. and Frabetti, P. L. and Gersabeck, E. and Goudzovski, E. and Hristov, P. and Kekelidze, V. and Kozhuharov, V. and Litov, L. and Madigozhin, D. and Misheva, M. and Molokanova, N. and Polenkevich, I. and Potrebenikov, Yu and Stoynev, S. and Zinchenko, A. and Monnier, E. and Winston, R. and Rubin, P. and Dalpiaz, P. and Damiani, C. and Fiorini, M. and Martini, M. and Petrucci, F. and Savrié, M. and Scarpa, M. and Wahl, H. and Baldini, W. and Cotta Ramusino, A. and Gianoli, A. and Calvetti, M. and Celeghini, E. and Ruggiero, G. (2019) First observation and study of the K ±  → π ± π 0 e + e − decay. Physics Letters B, 788. pp. 552-561. ISSN 0370-2693

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The NA48/2 experiment at CERN reports the first observation of the K ± →π ± π 0 e + e − decay from an exposure of 1.7×10 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 ± →π ± π 0 e + 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.

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Journal Article
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Physics Letters B
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Deposited On:
29 Mar 2019 09:00
Last Modified:
16 Sep 2020 05:22