New high statistics measurement of Ke4 decay form factors and ππ scattering phase shifts

J. R. Batley, A. J. Culling, 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. PatelA. Peters, S. Balev, P. L. Frabetti, E. Goudzovski, P. Hristov, V. Kekelidze, V. Kozhuharov, L. Litov, D. Madigozhin, E. Marinova, N. Molokanova, I. Polenkevich, Y. Potrebenikov, S. Stoynev, A. Zinchenko, E. Monnier, E. Swallow, R. Winston, P. Rubin, A. Walker, W. Baldini, A. Cotta Ramusino, P. Dalpiaz, C. Damiani, M. Fiorini, A. Gianoli, M. Martini, F. Petrucci, M. Savrié, M. Scarpa, H. Wahl, A. Bizzeti, M. Calvetti, E. Celeghini, E. Iacopini, M. Lenti, F. Martelli, G. Ruggiero, M. Veltri, M. Behler, K. Eppard, 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, Mayda Velasco, M. D. Wood, G. Anzivino, P. Cenci, E. Imbergamo, A. Nappi, M. Pepe, M. C. Petrucci, M. Piccini, M. Raggi, M. Valdata-Nappi, C. Cerri, G. Collazuol, F. Costantini, L. Dilella, N. Doble, R. Fantechi, L. Fiorini, S. Giudici, G. Lamanna, I. Mannelli, A. Michetti, G. Pierazzini, M. Sozzi, 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, S. Bifani, C. Biino, N. Cartiglia, M. Clemencic, S. Goy Lopez, F. Marchetto, H. Dibon, M. Jeitler, M. Markytan, I. Mikulec, G. Neuhofer, L. Widhalm

Research output: Contribution to journalArticlepeer-review

145 Scopus citations


We report results from a new measurement of the Ke4 decay K ±→π+π-e ±ν by the NA48/2 collaboration at the CERN SPS, based on a partial sample of more than 670∈000 Ke4 decays in both charged modes collected in 2003. The form factors of the hadronic current (F,G,H) and ππ phase difference (δ=δsp) have been measured in ten independent bins of the ππ mass spectrum to investigate their variation. A sizeable acceptance at large ππ mass, a low background and a very good resolution contribute to an improved experimental accuracy, a factor two better than in the previous measurement, when extracting the ππ scattering lengths a0 0 and a0 2. Under the assumption of isospin symmetry and using numerical solutions of the Roy equations, the following values are obtained in the plane (a0 0,a0 2): a0 0=0.233±0.016stat±0.007syst,a0 2=-0.0471±0.011stat±0.004syst. The presence of potentially large isospin effects is also considered and will allow comparison with precise predictions from Chiral Perturbation Theory.

Original languageEnglish (US)
Article number411
Pages (from-to)411-423
Number of pages13
JournalEuropean Physical Journal C
Issue number3
StatePublished - Apr 2008

ASJC Scopus subject areas

  • Engineering (miscellaneous)
  • Physics and Astronomy (miscellaneous)


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