Latest results on rare kaon decays from the NA48/2 experiment at CERN

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

The NA48/2 experiment at CERN reports the first observation of the K± ? p±p0e+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. 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. The most precise measurement of the charged kaon semi-leptonic form factors obtained by NA48/2 with 4.4 million Ke3 and 2.3 million Kµ3 events collected in 2004 will also be presented.

Latest results on rare kaon decays from the NA48/2 experiment at CERN / Raggi M., Anzivino G., Arcidiacono R., Baldini W., Balev S., Batley, Behler M., Bifani S., Biino C., Bizzeti A., Bloch-Devaux B., Bocquet G., Cabibbo N., Calvetti M., Cartiglia N., Ceccucci A., Cenci P., Cerri C., Cheshkov C., Cheze J.B., et al.. - In: POS PROCEEDINGS OF SCIENCE. - ISSN 1824-8039. - ELETTRONICO. - 390:(2021), pp. 1-6. (40th International Conference on High Energy Physics, ICHEP 2020 cze 2020).