First observation and branching fraction and decay parameter measurements of the weak radiative decay Ξ0 → Λ e+ e-

J. R. Batley, G. E. Kalmus, C. Lazzeroni, D. J. Munday, M. Patel, M. W. Slater, S. A. Wotton, R. Arcidiacono, G. Bocquet, A. Ceccucci, D. Cundy, N. Doble, V. Falaleev, L. Gatignon, A. Gonidec, P. Grafström, W. Kubischta, I. Mikulec, A. Norton, B. Panzer-SteindelP. Rubin*, H. Wahl, E. Goudzovski, P. Hristov, V. Kekelidze, L. Litov, D. Madigozhin, N. Molokanova, Yu Potrebenikov, S. Stoynev, A. Zinchenko, E. Monnier, E. Swallow, R. Winston, R. Sacco, A. Walker, W. Baldini, P. Dalpiaz, P. L. Frabetti, A. Gianoli, M. Martini, F. Petrucci, M. Savrié, M. Scarpa, A. Bizzeti, M. Calvetti, G. Collazuol, E. Iacopini, M. Lenti, G. Ruggiero, M. Veltri, M. Behler, K. Eppard, M. Eppard, A. Hirstius, K. Kleinknecht, U. Koch, P. Marouelli, L. Masetti, U. Moosbrugger, C. Morales Morales, A. Peters, R. Wanke, A. Winhart, A. Dabrowski, T. Fonseca Martin, M. Velasco, G. Anzivino, P. Cenci, E. Imbergamo, G. Lamanna, P. Lubrano, A. Michetti, A. Nappi, M. Pepe, M. C. Petrucci, M. Piccini, M. Valdata, C. Cerri, F. Costantini, R. Fantechi, L. Fiorini, S. Giudici, I. Mannelli, G. Pierazzini, M. Sozzi, C. Cheshkov, J. B. Cheze, M. De Beer, P. Debu, G. Gouge, G. Marel, E. Mazzucato, B. Peyaud, B. Vallage, M. Holder, A. Maier, M. Ziolkowski, C. Biino, N. Cartiglia, M. Clemencic, S. Goy Lopez, F. Marchetto, E. Menichetti, N. Pastrone, W. Wislicki, H. Dibon, M. Jeitler, M. Markytan, G. Neuhofer, L. Widhalm

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


The weak radiative decay Ξ0 → Λ e+ e- has been detected for the first time. We find 412 candidates in the signal region, with an estimated background of 15 ± 5 events. We determine the branching fraction B (Ξ0 → Λ e+ e-) = [7.6 ± 0.4 (stat) ± 0.4 (syst) ± 0.2 (norm)] × 10-6, consistent with an internal bremsstrahlung process, and the decay asymmetry parameter αΞ Λ e e = - 0.8 ± 0.2, consistent with that of Ξ0 → Λ γ. The charge conjugate reaction over(Ξ0, -) → over(Λ, -) e+ e- has also been observed.

Original languageEnglish (US)
Pages (from-to)1-8
Number of pages8
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Issue number1
StatePublished - Jun 21 2007

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

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