Study of the production of Λ0b and B฀฀฀0 hadrons in pp collisions and first measurement of the Λ0b→J/฀pK− branching fraction

Abstract

The product of the Λ (B ) differential production cross-section and the branching fraction of the decay Λ → J/ψ pK (B → J/ψ K (892) ) is measured as a function of the beauty hadron transverse momentum, p , and rapidity, y. The kinematic region of the measurements is p < 20 GeV/c and 2.0 < y < 4.5. The measurements use a data sample corresponding to an integrated luminosity of 3 fb collected by the LHCb detector in pp collisions at centre-of-mass energies √s = 7 TeV in 2011 and √s = 8 TeV in 2012. Based on previous LHCb results of the fragmentation fraction ratio, f 0 /f , the branching fraction of the decay Λ → J/ψ pK is measured to be B(Λ → J/ψ pK ) = (3.17 ± 0.04 ± 0.07 ± 0.34 ) × 10 , where the first uncertainty is statistical, the second is systematic, the third is due to the uncertainty on the branching fraction of the decay B → J/ψ K (892) , and the fourth is due to the knowledge of f 0 /f . The sum of the asymmetries in the production and decay between Λ and Λ is also measured as a function of p and y. The previously published branching fraction of Λ → J/ψ pπ , relative to that of Λ → J/ψ pK , is updated. The branching fractions of Λ → P (→ J/ψ p)K are determined. 0 0 0 − 0 * 0 −1 0 − 0 − +0 45 −4 0 * 0 0 0 0 − 0 − 0 + − b b T T Λ b d b b −0 28 Λ b d b b T b b b c