A sample of 65210 K ± → π 0 π 0 e ± ν (K e4 00 ) decay candidates with 1% background contamination has been collected in 2003-2004 by the NA48/2 collaboration at the CERN SPS. A study of the differential rate provides the first measurement of the hadronic form factor variation in the plane (M ππ 2 , M eν 2 ) and brings evidence for a cusp-like structure in the distribution of the squared π 0 π 0 invariant mass around 4m2π+ . Exploiting a model independent description of this form factor, the branching ratio, inclusive of radiative decays, is obtained using the K ± → π 0 π 0 π ± decay mode as normalization. It is measured to be BR(K e4 00 ) = (2.552 ± 0.010stat ± 0.010syst ± 0.032ext) × 10−5, which improves the current world average precision by an order of magnitude while the 1.4% relative precision is dominated by the external uncertainty from the normalization mode. A comparison with the properties of the corresponding mode involving a π + π − pair (K e4 + − ) is also presented.

Detailed study of the K± → π° π° e± ν (Ke4 00) decay properties

BALDINI, Wander;COTTA RAMUSINO, Angelo;DALPIAZ, Pietro;FIORINI, Massimiliano;GIANOLI, Alberto;PETRUCCI, Ferruccio Carlo;SAVRIE', Mauro;
2014

Abstract

A sample of 65210 K ± → π 0 π 0 e ± ν (K e4 00 ) decay candidates with 1% background contamination has been collected in 2003-2004 by the NA48/2 collaboration at the CERN SPS. A study of the differential rate provides the first measurement of the hadronic form factor variation in the plane (M ππ 2 , M eν 2 ) and brings evidence for a cusp-like structure in the distribution of the squared π 0 π 0 invariant mass around 4m2π+ . Exploiting a model independent description of this form factor, the branching ratio, inclusive of radiative decays, is obtained using the K ± → π 0 π 0 π ± decay mode as normalization. It is measured to be BR(K e4 00 ) = (2.552 ± 0.010stat ± 0.010syst ± 0.032ext) × 10−5, which improves the current world average precision by an order of magnitude while the 1.4% relative precision is dominated by the external uncertainty from the normalization mode. A comparison with the properties of the corresponding mode involving a π + π − pair (K e4 + − ) is also presented.
J. R., Batley; G., Kalmus; C., Lazzeroni; D. J., Munday; M. W., Slater; S. A., Wotton; R., Arcidiacono; G., Bocquet; N., Cabibbo; A., Ceccucci; D., Cundy; V., Falaleev; M., Fidecaro; L., Gatignon; A., Gonidec; W., Kubischta; A., Norton; A., Maier; M., Patel; A., Peters; S., Balev; P. L., Frabetti; E., Gersabeck; E., Goudzovski; P., Hristov; V., Kekelidze; V., Kozhuharov; L., Litov; D., Madigozhin; N., Molokanova; I., Polenkevich; Potrebenikov, Y. u.; S., Stoynev; A., Zinchenko; E., Monnier; E., Swallow; R., Winston; P., Rubin; A., Walker; Baldini, Wander; COTTA RAMUSINO, Angelo; Dalpiaz, Pietro; C., Damiani; Fiorini, Massimiliano; Gianoli, Alberto; M., Martini; Petrucci, Ferruccio Carlo; Savrie', Mauro; M., Scarpa; H., Wahl; A., Bizzeti; M., Lenti; M., Veltri; M., Calvetti; E., Celeghini; E., Iacopini; G., Ruggiero; M., Behler; K., Eppard; M., Gersabeck; K., Kleinknecht; P., Marouelli; L., Masetti; U., Moosbrugger; C., Morales Morales; B., Renk; M., Wache; R., Wanke; A., Winhart; D., Coward; A., Dabrowski; T., Fonseca Martin; M., Shieh; M., Szleper; M., Velasco; M. D., Wood; P., Cenci; M., Pepe; M. C., Petrucci; G., Anzivino; E., Imbergamo; A., Nappi; M., Piccini; M., Raggi; M., Valdata Nappi; C., Cerri; R., Fantechi; G., Collazuol; L., Dilella; G., Lamanna; I., Mannelli; A., Michetti; F., Costantini; N., Doble; L., Fiorini; S., Giudici; G., Pierazzini; M., Sozzi; S., Venditti; B., Bloch Devaux; C., Cheshkov; J. B., Chèze; M., De Beer; J., Derré; G., Marel; E., Mazzucato; B., Peyaud; B., Vallage; M., Holder; M., Ziolkowski; C., Biino; N., Cartiglia; F., Marchetto; S., Bifani; M., Clemencic; S., Goy Lopez; H., Dibon; M., Jeitler; M., Markytan; I., Mikulec; G., Neuhofer; L., Widhalm
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/2183012
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