Study of the production of Λ0b and B0 hadrons in pp collisions and first measurement of the Λ0b → J/ψpK− branching fraction


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The product of the differential production cross-section and the branching fraction of the decay Λ0b → J/ψpK − (B0 → J/ψK∗ (892)0) is measured as a function of the beauty hadron transverse momentum, pT, and rapidity, y. The kinematic region of the measurements is pT < 20 GeV/c and 2.0 < y < 4.5. The measurements use a data sample corresponding to an integrated luminosity of 3fb−1 collected by the LHCb detector in pp collisions at centre-of-mass energies in 2011 and √s = 8 TeV in 2012. Based on previous LHCb results of the fragmentation fraction ratio, fΛ0B/fd, the branching fraction of the decay Λ0b →J/ψpK− is measured to be
B(Λ0b→J/ψpK−)=(3.17±0.04±0.07±0.34+0.45−0.28 )×10−4

where the first uncertainty is statistical, the second is systematic, the third is due to the uncertainty on the branching fraction of the decay B̅0 → J/ψK̅*(892)0, and the fourth is due to the knowledge of fΛ0b/fd. The sum of the asymmetries in the production and decay between Λ0b and Λ¯0 b is also measured as a function of pT and y. The previously published branching fraction of Λ0b → J/ψpπ−, relative to that of, is updated. The branching fractions of Λ0b → P+c (→J/ψp)K − are determined.
Date made available4 Jan 2016

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