Measurement of the production fraction times branching fraction f(b -> Λ_b) x B(Λ_b -> J/ψΛ)

Abstract: A new measurement of the b -> \Lambda_b production fraction multiplied by the \Lambda_b -> J/\psi \Lambda branching fraction was performed by the D0 experiment using 6.1 fb^{-1} of p\bar{p} collisions at \sqrt{s} = 1.96 TeV. The result of this measurement, f(b -> \Lambda_b) x B(\Lambda_b -> J/\psi \Lambda) = [6.01 {\pm} 0.60 (stat.) {\pm} 0.58 (syst.) {\pm} 0.28 (PDG)] x 10^{-5}, represents an improvement in precision by about a factor of three with respect to the current world average. We give an estimate of B(\Lambda_b -> J/\psi \Lambda), which takes into account correlations among the different b-hadron production fractions and other weakly decaying baryons.