European Physical Journal C: Particles and Fields (2018-03-01)

Observation of $$\Xi _{c}(2930)^0$$ Ξc(2930)0 and updated measurement of $$B^{-} \rightarrow K^{-} \Lambda _{c}^{+} \bar{\Lambda }_{c}^{-}$$ B-→K-Λc+Λ¯c- at Belle

  • Y. B. Li,
  • C. P. Shen,
  • I. Adachi,
  • J. K. Ahn,
  • H. Aihara,
  • S. Al Said,
  • D. M. Asner,
  • T. Aushev,
  • R. Ayad,
  • V. Babu,
  • I. Badhrees,
  • A. M. Bakich,
  • Y. Ban,
  • V. Bansal,
  • P. Behera,
  • M. Berger,
  • V. Bhardwaj,
  • B. Bhuyan,
  • J. Biswal,
  • G. Bonvicini,
  • A. Bozek,
  • M. Bračko,
  • T. E. Browder,
  • D. Červenkov,
  • V. Chekelian,
  • A. Chen,
  • B. G. Cheon,
  • K. Chilikin,
  • K. Cho,
  • S.-K. Choi,
  • Y. Choi,
  • D. Cinabro,
  • S. Cunliffe,
  • N. Dash,
  • S. Di Carlo,
  • Z. Doležal,
  • Z. Drásal,
  • S. Eidelman,
  • D. Epifanov,
  • J. E. Fast,
  • T. Ferber,
  • B. G. Fulsom,
  • R. Garg,
  • V. Gaur,
  • N. Gabyshev,
  • A. Garmash,
  • M. Gelb,
  • A. Giri,
  • P. Goldenzweig,
  • E. Guido,
  • J. Haba,
  • T. Hara,
  • K. Hayasaka,
  • H. Hayashii,
  • M. T. Hedges,
  • W.-S. Hou,
  • T. Iijima,
  • K. Inami,
  • G. Inguglia,
  • A. Ishikawa,
  • R. Itoh,
  • M. Iwasaki,
  • Y. Iwasaki,
  • W. W. Jacobs,
  • S. Jia,
  • Y. Jin,
  • K. K. Joo,
  • T. Julius,
  • G. Karyan,
  • Y. Kato,
  • T. Kawasaki,
  • H. Kichimi,
  • C. Kiesling,
  • D. Y. Kim,
  • J. B. Kim,
  • K. T. Kim,
  • S. H. Kim,
  • K. Kinoshita,
  • P. Kodyš,
  • S. Korpar,
  • D. Kotchetkov,
  • P. Križan,
  • R. Kroeger,
  • P. Krokovny,
  • R. Kulasiri,
  • T. Kumita,
  • A. Kuzmin,
  • Y.-J. Kwon,
  • I. S. Lee,
  • S. C. Lee,
  • L. K. Li,
  • L. Li Gioi,
  • J. Libby,
  • D. Liventsev,
  • M. Lubej,
  • T. Luo,
  • J. MacNaughton,
  • M. Masuda,
  • T. Matsuda,
  • M. Merola,
  • K. Miyabayashi,
  • H. Miyata,
  • R. Mizuk,
  • G. B. Mohanty,
  • H. K. Moon,
  • T. Mori,
  • M. Mrvar,
  • R. Mussa,
  • E. Nakano,
  • M. Nakao,
  • T. Nanut,
  • K. J. Nath,
  • Z. Natkaniec,
  • M. Nayak,
  • M. Niiyama,
  • S. Nishida,
  • S. Ogawa,
  • P. Pakhlov,
  • G. Pakhlova,
  • B. Pal,
  • S. Pardi,
  • C. W. Park,
  • H. Park,
  • S. Paul,
  • T. K. Pedlar,
  • R. Pestotnik,
  • L. E. Piilonen,
  • V. Popov,
  • A. Rostomyan,
  • G. Russo,
  • Y. Sakai,
  • M. Salehi,
  • S. Sandilya,
  • L. Santelj,
  • T. Sanuki,
  • O. Schneider,
  • G. Schnell,
  • C. Schwanda,
  • Y. Seino,
  • V. Shebalin,
  • T.-A. Shibata,
  • J.-G. Shiu,
  • B. Shwartz,
  • A. Sokolov,
  • E. Solovieva,
  • M. Starič,
  • J. F. Strube,
  • M. Sumihama,
  • T. Sumiyoshi,
  • M. Takizawa,
  • U. Tamponi,
  • K. Tanida,
  • F. Tenchini,
  • M. Uchida,
  • T. Uglov,
  • Y. Unno,
  • S. Uno,
  • C. Van Hulse,
  • G. Varner,
  • V. Vorobyev,
  • A. Vossen,
  • E. Waheed,
  • B. Wang,
  • C. H. Wang,
  • M.-Z. Wang,
  • P. Wang,
  • X. L. Wang,
  • M. Watanabe,
  • Y. Watanabe,
  • E. Widmann,
  • E. Won,
  • H. Ye,
  • J. Yelton,
  • C. Z. Yuan,
  • Y. Yusa,
  • S. Zakharov,
  • Z. P. Zhang,
  • V. Zhilich,
  • V. Zhukova,
  • V. Zhulanov

DOI
https://doi.org/10.1140/epjc/s10052-018-5720-5
Journal volume & issue
Vol. 78, no. 3
pp. 1 – 8

Abstract

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Abstract We report the first observation of the $$\Xi _{c}(2930)^0$$ Ξc(2930)0 charmed-strange baryon with a significance greater than 5$$\sigma $$ σ . The $$\Xi _{c}(2930)^0$$ Ξc(2930)0 is found in its decay to $$K^- \Lambda _{c}^+$$ K-Λc+ in $$B^{-} \rightarrow K^{-} \Lambda _{c}^{+} \bar{\Lambda }_{c}^{-}$$ B-→K-Λc+Λ¯c- decays. The measured mass and width are $$[2928.9 \pm 3.0(\mathrm stat.)^{+0.9}_{-12.0}(\mathrm syst.)]$$ [2928.9±3.0(stat.)-12.0+0.9(syst.)] MeV/$$c^{2}$$ c2 and $$[19.5 \pm 8.4(\mathrm stat.) ^{+5.9}_{-7.9}(\mathrm syst.)]$$ [19.5±8.4(stat.)-7.9+5.9(syst.)] MeV, respectively, and the product branching fraction is $$\mathcal{B}(B^{-} \rightarrow \Xi _{c}(2930)^0 \bar{\Lambda }_{c}^{-}) \mathcal{B}(\Xi _{c}(2930)^0 \rightarrow K^- \Lambda _{c}^{+})=[1.73 \pm 0.45(\mathrm stat.) \pm 0.21(\mathrm syst.)]\times 10^{-4}$$ B(B-→Ξc(2930)0Λ¯c-)B(Ξc(2930)0→K-Λc+)=[1.73±0.45(stat.)±0.21(syst.)]×10-4 . We also measure $$\mathcal{B}(B^{-} \rightarrow K^{-} \Lambda _{c}^{+} \bar{\Lambda }_{c}^{-}) = [4.80 \pm 0.43(\mathrm stat.) \pm 0.60(\mathrm syst.)] \times 10^{-4}$$ B(B-→K-Λc+Λ¯c-)=[4.80±0.43(stat.)±0.60(syst.)]×10-4 with improved precision, and search for the charmonium-like state Y(4660) and its spin partner, $$Y_{\eta }$$ Yη , in the $$\Lambda _{c}^{+}\bar{\Lambda }_{c}^{-}$$ Λc+Λ¯c- invariant mass spectrum. No clear signals of the Y(4660) nor its spin partner are observed and the 90% credibility level (C.L.) upper limits on their production rates are determined. These measurements are obtained from a sample of $$(772\pm 11)\times 10^{6} B\bar{B}$$ (772±11)×106BB¯ pairs collected at the $$\Upsilon (4S)$$ Υ(4S) resonance by the Belle detector at the KEKB asymmetric energy electron–positron collider.