Observation of J/ψp resonances consistent with pentaquark states in Λ[0 over b] → J/ψK[superscript -]p decays
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PhysRevLett.115.072001.pdf
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Author(s)
Aaij, R.
Adeva, B.
Adinolfi, M.
Affolder, A.
Ajaltouni, Z.
Akar, S.
Albrecht, J.
Alessio, F.
Alexander, M.
Ali, S.
Date Issued
August 2015
Journal
Physical Review Letters
Publisher
American Physical Society
Citation
Aaij, R., B. Adeva, M. Adinolfi, A. Affolder, Z. Ajaltouni, S. Akar, J. Albrecht, et al. “Observation of J/ψp Resonances Consistent with Pentaquark States in Λ[0 over b] → J/ψK[superscript −]p Decays.” Physical Review Letters 115, no. 7 (August 2015). © 2015 CERN, for the LHCb Collaboration
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Final published version
Abstract
Observations of exotic structures in the J/ψp channel, which we refer to as charmonium-pentaquark states, in Λ[0 over b] → J/ψK[superscript -]p decays are presented. The data sample corresponds to an integrated luminosity of 3 fb[superscript -1] acquired with the LHCb detector from 7 and 8 TeV pp collisions. An amplitude analysis of the three-body final state reproduces the two-body mass and angular distributions. To obtain a satisfactory fit of the structures seen in the J/ψp mass spectrum, it is necessary to include two Breit-Wigner amplitudes that each describe a resonant state. The significance of each of these resonances is more than 9 standard deviations. One has a mass of 4380 ± 8 ± 29 MeV and a width of 205 ± 18 ± 86 MeV, while the second is narrower, with a mass of 4449.8 ± 1.7 ± 2.5 MeV and a width of 39 ± 5 ± 19 MeV. The preferred J[superscript P] assignments are of opposite parity, with one state having spin 3/2 and the other 5/2.
MIT Department
Massachusetts Institute of Technology. Department of Physics
Massachusetts Institute of Technology. Laboratory for Nuclear Science
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DOI of Published Version
http://dx.doi.org/10.1103/PhysRevLett.115.072001
