Measurement of the mass and production rate of Ξ[overline b]
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PhysRevD.99.052006.pdf
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Author(s)
Boettcher, Thomas Julian
Craik, Daniel C
Weisser, Constantin
LHCB Collaboration
Date Issued
March 2019
Journal
Physical Review D
Publisher
American Physical Society
Citation
R. Aaij et al. "Measurement of the mass and production rate of Ξ[overline b]." Physical Review D 99, 5 (March 2019): 052006 © 2019 CERN, for the LHCb Collaboration
Version
Final published version
Abstract
The first measurement of the production rate of Ξ[overline b]⁻ baryons in pp collisions relative to that of Λ[subscript b]⁰ baryons is reported, using data samples collected by the LHCb experiment, and corresponding to integrated luminosities of 1, 2 and 1.6 fb⁻¹ at sqrt[s]=7, 8 and 13 TeV, respectively. In the kinematic region 2<η<6 and p[subscript T]<20 GeV/c, we measure f[subscript Ξ[overline b]⁻]/f[subscript Λ[subscript b]⁰ ] B(Ξ[subscript b]⁻→J/ψΞ⁻)/B(Λ[subscript b]⁰→J/ψΛ)=(10.8±0.9±0.8)×10⁻² √s =7,8 TeV], f [subscript Ξ[subscript b]⁻]/f[subscript Λ[subscript b⁰]B(Ξ[subscript b]⁻→J/ψΞ⁻)/B(Λ[subscript b⁰]→J/ψΛ)=(13.1±1.1±1.0)×10⁻² [√s =13 TeV], where f[subscript Ξ[overline b]⁻] and f[subscript Λ[subscript b⁰]] are the fragmentation fractions of b quarks into Ξ[subscript b]⁻ and Λ[subscript b⁰] baryons, respectively; B represents branching fractions; and the uncertainties are due to statistical and experimental systematic sources. The values of f[subscript Ξ[overline b]⁻]/f [subscript Λ[subscript b⁰] are obtained by invoking SU(3) symmetry in the Ξ[overline b]⁻→J/ψΞ⁻ and Λ[subscript b⁰]→J/ψΛ decays. Production asymmetries between Ξ[overline b]⁻ and Ξ[overline b]⁺ baryons are also reported. The mass of the Ξ[overline b]⁻ baryon is also measured relative to that of the Λ[subscript b⁰] baryon, from which it is found that m(Ξ[overline b]⁻)=5796.70±0.39±0.15±0.17 MeV/c², where the last uncertainty is due to the precision on the known Λ[subscript b⁰] mass. This result represents the most precise determination of the Ξ[overline b]⁻mass.
MIT Department
Massachusetts Institute of Technology. Department of Physics
Massachusetts Institute of Technology. Department of Nuclear Science and Engineering
Massachusetts Institute of Technology. Laboratory for Nuclear Science
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Creative Commons Attribution 3.0 unported license
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DOI of Published Version
https://doi.org/10.1103/PhysRevD.99.052006
