First observation of the isospin violating decay J/psi -> Lambda(Sigma)over-bar(0) + c.c.

M. Ablikim*, M. N. Achasov, D. J. Ambrose, F. F. An, Q. An, Z. H. An, J. Z. Bai, Y. Ban, J. Becker, N. Berger, M. Bertani, J. M. Bian, E. Boger, O. Bondarenko, I. Boyko, R. A. Briere, V. Bytev, X. Cai, O. Cakir, A. CalcaterraG. F. Cao, S. A. Cetin, J. F. Chang, G. Chelkov, G. Chen, H. S. Chen, J. C. Chen, M. L. Chen, S. J. Chen, Y. Chen, Y. B. Chen, H. P. Cheng, Y. P. Chu, D. Cronin-Hennessy, H. L. Dai, J. P. Dai, D. Dedovich, Z. Y. Deng, A. Denig, I. Denysenko, M. Destefanis, W. M. Ding, Y. Ding, L. Y. Dong, M. Y. Dong, S. X. Du, N. Kalantar-Nayestanaki, M. Kavatsyuk, H. Loehner, J. G. Messchendorp, Collaboration, B

*Corresponding author for this work

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Abstract

Using a sample of (225.2 +/- 2.8) x 10(6) J/psi events collected with the BESIII detector, we present results of a study of J/psi -> gamma Lambda(Lambda) over bar and report the first observation of the isospin violating decay J/psi -> Lambda(Sigma) over bar (0) + c.c., in which (Sigma) over bar (0) decays to gamma (Lambda) over bar. The measured branching fractions are B(J/psi -> (Lambda) over bar Sigma(0)) = (1.46 +/- 0.11 +/- 0.12) x 10(-5) and B(J/psi -> Lambda(Sigma) over bar (0)) = (1.37 +/- 0.12 +/- 0.11) x 10(-5). We search for Lambda(1520) -> gamma Lambda decay, and find no evident signal, and an upper limit for the product branching fraction B(J/psi -> Lambda(Lambda) over bar (1520) + c.c) x B(Lambda(1520) -> gamma Lambda) <4.1 x 10(-6) is set at the 90% confidence level. We also report the observation of eta(c) -> Lambda in J/psi -> gamma eta(c), eta(c) -> Lambda(Lambda) over bar and measure the branching fraction B(eta(c) -> Lambda(Lambda) over bar) = (1.16 +/- 0.12(stat) +/- 0.19(syst) +/- 0.28(PDG)) x 10(-3).

Original languageEnglish
Article number032008
Number of pages10
JournalPhysical Review D
Volume86
Issue number3
DOIs
Publication statusPublished - 15-Aug-2012

Keywords

  • ELECTROMAGNETIC DECAYS
  • EXCITED HYPERONS
  • RADIATIVE DECAY
  • QUARK-MODEL
  • BARYONS

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