Observation of two new Ξ-b baryon resonances

LHCb Collaboration, R. Aaij, B. Adeva, M. Adinolfi, A. Affolder, Z. Ajaltouni, S. Akar, J. Albrecht, F. Alessio, M. Alexander, S. Ali, G. Alkhazov, P. Alvarez Cartelle, A. A. Alves, S. Amato, S. Amerio, Y. Amhis, L. An, L. Anderlini, J. AndersonR. Andreassen, M. Andreotti, J. E. Andrews, R. B. Appleby, O. Aquines Gutierrez, F. Archilli, A. Artamonov, M. Artuso, E. Aslanides, G. Auriemma, M. Baalouch, S. Bachmann, J. J. Back, A. Badalov, C. Baesso, W. Baldini, R. J. Barlow, C. Barschel, S. Barsuk, W. Barter, V. Batozskaya, S. Bifani, N. Farley, P. Griffith, I. R. Kenyon, C. Lazzeroni, A. Mazurov, J. McCarthy, C. J. Parkinson, L. Pescatore, N. K. Watson

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Abstract

Two structures are observed close to the kinematic threshold in the Ξ0bπ- mass spectrum in a sample of proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb-1, recorded by the LHCb experiment. In the quark model, two baryonic resonances with quark content bds are expected in this mass region: the spin-parity JP=(1/2)+ and JP=(3/2)+ states, denoted Ξb- and Ξb-. Interpreting the structures as these resonances, we measure the mass differences and the width of the heavier state to be m(Ξb-)-m(Ξ0b)-m(π-)=3.653±0.018±0.006 MeV/c2, m(Ξb-)-m(Ξ0b)-m(π-)=23.96±0.12±0.06 MeV/c2, Γ(Ξb-)=1.65±0.31±0.10 MeV, where the first and second uncertainties are statistical and systematic, respectively. The width of the lighter state is consistent with zero, and we place an upper limit of Γ(Ξb-)<0.08 MeV at 95% confidence level. Relative production rates of these states are also reported.

Original languageEnglish
Article number062004
Number of pages9
JournalPhysical Review Letters
Volume114
Issue number6
DOIs
Publication statusPublished - 10 Feb 2015

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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