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Batley, J R; Kalmus, G; Lazzeroni, C; Munday, D J; Slater, M W; Wotton, SA; Arcidiacono, R; Bocquet, G; Cabibbo, N; Ceccucci, A; Cundy, D; Falaleev, V; Fidecaro, M; Gatignon, L; Gonidec, A; Kubischta, W; Norton, A; Maier, A; Patel, M; Peters, A; Balev, S; Frabetti, P L; Gersabeck, E; 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; Baldini, W; Cotta Ramusino, A; Dalpiaz, P; Damiani, C; Fiorini, M; Gianoli, A; Martini, M; Petrucci, F; Savrie, M; Scarpa, M; Wahl, H
Physics letters. B, 08/2012, Letnik: 715, Številka: 1-3Journal Article
A sample of more than one million K +/- ? p + p - e +/- ? (K e 4) decay candidates with less than one percent background contamination has been collected by the NA48/2 experiment at the CERN SPS in 2003-2004, allowing a detailed study of the decay properties. The branching ratio, inclusive of K e 4 gamma decays, is measured to be BR (K e 4) = (4.257 +/- 0.016 exp +/- 0.031 ext) X 10 - 5 with a total relative error of 0.8 % . This measurement complements the study of S- and P-wave hadronic form factors by assigning absolute values to the relative hadronic form factors obtained earlier in a simultaneous analysis of the pp scattering lengths conducted on the same data sample. The overall form factor normalization f s = 5.705 +/- 0.017 exp +/- 0.031 ext is obtained with a total relative precision of 0.6 % .
