Observation of Two New Ξ [subscript b][superscript −] Baryon Resonances
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PhysRevLett.114.062004.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
February 2015
Journal
Physical Review Letters
Publisher
American Physical Society
Citation
Aaij, R. et al. “Observation of Two New Ξ [subscript b][superscript −] Baryon Resonances.” Physical Review Letters 114.6 (2015).
Version
Final published version
Abstract
Two structures are observed close to the kinematic threshold in the Ξ[0 over b]π[superscript -] mass spectrum in a sample of proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb[superscript -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 J[superscript P] = ([1 over 2])[superscript +] and J[superscript P] = ([3 over 2])[superscript +] states, denoted Ξ'[subscript b][superscript -] and Ξ*[subscript b][superscript -]. Interpreting the structures as these resonances, we measure the mass differences and the width of the heavier state to be m(Ξ'[subscript b][superscript -]) - m(Ξ[0 over b]) - m(π[superscript -]) = 3.653 ± 0.018 ± 0.006 [MeV over c [superscript 2]], m(Ξ[* over b]) - m(Ξ[0 over b]) - m(π[superscript -]) = 23.96 ± 0.12 ± 0.06 [MeV over c [superscript 2]], Γ(Ξ[* over b][superscript -]) = 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(Ξ'[subscript b][superscript -]) < 0.08 MeV at 95% confidence level. Relative production rates of these states are also reported.
MIT Department
Massachusetts Institute of Technology. Department of Physics
Massachusetts Institute of Technology. Laboratory for Nuclear Science
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http://dx.doi.org/10.1103/PhysRevLett.114.062004
