Publications associated with TORCH

Observation of the Ξb−→J/ψΛK− decay

Physics Letters B Elsevier 772 (2017) 265-273

R Aaij, B Adeva, M Adinolfi, T Evans, P Gandini, BR Gruberg Cazon, T Hadavizadeh, N Harnew, DR Hill, PG Jalocha, MJJ John, NP Jurik, S Malde, AK Nandi, A Rollings, S Topp-Joergensen, G Veneziano, GR Wilkinson

The observation of the decay Ξ b − →J/ψΛK − is reported, using a data sample corresponding to an integrated luminosity of 3fb −1 , collected by the LHCb detector in pp collisions at centre-of-mass energies of 7 and 8TeV. The production rate of Ξ b − baryons detected in the decay Ξ b − →J/ψΛK − is measured relative to that of Λ b 0 baryons using the decay Λ b 0 →J/ψΛ. Integrated over the b-baryon transverse momentum p T < 25GeV/c and rapidity 2.0 < y < 4.5, the measured ratio is [Formula presented][Formula presented] =(4.19±0.29 (stat)±0.15 (syst))×10 −2 , where f Ξ b − and f Λ b 0 are the fragmentation fractions of b→Ξ b − and b→Λ b 0 transitions, and B represents the branching fraction of the corresponding b-baryon decay. The mass difference between Ξ b − and Λ b 0 baryons is measured to be M(Ξ b − )−M(Λ b 0 )=177.08±0.47 (stat)±0.16 (syst)MeV/c 2 .

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