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Culling, A.J.; Kalmus, G.; Lazzeroni, C.; Munday, D.J.; Slater, M.W.; Wotton, S.A.; Arcidiacono, R.; Bocquet, G.; Cabibbo, N.; Ceccucci, A.; Cundy, D.; Falaleev, V.; Fidecaro, M.; Gatignon, L.; Gonidec, A.; Kubischta, W.; Maier, A.; Patel, M.; Peters, A.; Balev, S.; Goudzovski, E.; Hristov, P.; Kekelidze, V.; Kozhuharov, V.; Litov, L.; Madigozhin, D.; Molokanova, N.; Polenkevich, I.; Potrebenikov, Yu; Stoynev, S.; Zinchenko, A.; Monnier, E.; Swallow, E.; Winston, R.; Rubin, P.; Walker, A.; Ramusino, A. Cotta; Damiani, C.; Martini, M.; Petrucci, F.; Savrié, M.; Scarpa, M.; Wahl, H.; Bizzeti, A.; Calvetti, M.; Celeghini, E.; Iacopini, E.; Lenti, M.; Veltri, M.; Behler, M.; Eppard, K.; Marouelli, P.; Masetti, L.; Moosbrugger, U.; Morales, C. Morales; Renk, B.; Wache, M.; Wanke, R.; Winhart, A.; Shieh, M.; Szleper, M.; Velasco, M.; Wood, M.D.; Anzivino, G.; Cenci, P.; Imbergamo, E.; Pepe, M.; Petrucci, M.C.; Raggi, M.; Cerri, C.; Fantechi, R.; Collazuol, G.; DiLella, L.; Lamanna, G.; Mannelli, I.; Michetti, A.; Costantini, F.; Doble, N.; Fiorini, L.; Giudici, S.; Pierazzini, G.; Sozzi, M.; Venditti, S.; Bloch-Devaux, B.; Cheshkov, C.; De Beer, M.; Derré, J.; Marel, G.; Vallage, B.; Ziolkowski, M.; Bifani, S.; Cartiglia, N.; Clemencic, M.; Lopez, S. Goy; Marchetto, F.; Jeitler, M.; Markytan, M.; Mikulec, I.; Neuhofer, G.; Widhalm, L.
Physics letters. B, 06/2009, Letnik: 677, Številka: 5Journal Article
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=(Mee/MK)2, was parameterized according to several models, and, in particular, the slope δ of the linear form factor W(z)=W0(1+δz) 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.
