New measurement of the K±→π+π−e±ν(Ke4) decay branching ratio and hadronic form factors

• Published in: Physics letters. B 2012-08, Vol.715 (1-3), p.105-115
• Main Authors: Kalmus, G., Lazzeroni, C., Munday, D.J., Wotton, S.A., Cabibbo, N., Ceccucci, A., Fidecaro, M., Gatignon, L., Kubischta, W., Maier, A., Patel, M., Peters, A., Frabetti, P.L., Gersabeck, E., Goudzovski, E., Kekelidze, V., Kozhuharov, V., Litov, L., Madigozhin, D., Molokanova, N., Polenkevich, I., 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., Scarpa, M., Wahl, H., Bizzeti, A., Lenti, M., Veltri, M., Calvetti, M., Iacopini, E., Ruggiero, G., Behler, M., Kleinknecht, K., Masetti, L., Moosbrugger, U., Morales Morales, C., Renk, B., Wache, M., Wanke, R., Winhart, A., Coward, D., Dabrowski, A., Fonseca Martin, T., Shieh, M., Szleper, M., Velasco, M., Pepe, M., Petrucci, M.C., Anzivino, G., Imbergamo, E., Nappi, A., Piccini, M., Raggi, M., Valdata-Nappi, M., Fantechi, R., Collazuol, G., DiLella, L., Lamanna, G., Mannelli, I., Michetti, A., Costantini, F., Giudici, S., Pierazzini, G., Sozzi, M., Venditti, S., Bloch-Devaux, B., Cheshkov, C., Chèze, J.B., De Beer, M., Derré, J., Marel, G., Mazzucato, E., Peyaud, B., Vallage, B., Holder, M., Ziolkowski, M., Biino, C., Cartiglia, N., Marchetto, F., Bifani, S., Goy Lopez, S., Dibon, H., Jeitler, M., Markytan, M., Mikulec, I., Neuhofer, G., Widhalm, L.
• Format: Article
• Language: English
• Subjects: Branching ratio; Exact sciences and technology; Hadronic form factors; Kaon rare decays; Nuclear physics; Physics; Semileptonic [formula omitted] decay; The physics of elementary particles and fields
• ISSN: 0370-2693; 1873-2445
• DOI: 10.1016/j.physletb.2012.07.048

A sample of more than one million K±→π+π−e±ν (Ke4) 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 Ke4γ decays, is measured to be BR(Ke4)=(4.257±0.016exp±0.031ext)×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 ππ scattering lengths conducted on the same data sample. The overall form factor normalization fs=5.705±0.017exp±0.031ext is obtained with a total relative precision of 0.6%.