Abstract
The product of the differential production cross-section and the branching fraction of the decay 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 in 2012. Based on previous LHCb results of the fragmentation fraction ratio the branching fraction of the decay is measured to bewhere 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 . The sum of the asymmetries in the production and decay between and is also measured as a function of pT and y. The previously published branching fraction of , relative to that of , is updated. The branching fractions of are determined.
Highlights
In quantum chromodynamics (QCD) the production process of b hadrons can be divided into two steps, assuming factorisation: a hard process for b production and a soft process to describe hadronisation
The hard process can be predicted by perturbative calculations in QCD; the soft process is parameterised by the fragmentation function, which has large uncertainties due to nonperturbative QCD contributions
Leading-order QCD calculations predict equal production cross-sections for heavy baryons and heavy anti-baryons, while measurements at the ISR showed that Λ+c production is favoured in pp collisions at forward rapidity, y [3, 4]
Summary
In quantum chromodynamics (QCD) the production process of b hadrons can be divided into two steps, assuming factorisation: a hard process for b production and a soft process to describe hadronisation. The LHCb experiment measured the ratio of Λ0b baryon production to light B meson production, fΛ0b /(fu+fd) [7]. The kinematic dependence of the ratio of Λ0b to B0 production, fΛ0b /fd, was measured using Λ0b →Λ+c π− and B0 →D+π− decays, and the absolute branching fraction B(Λ0b → Λ+c π−) was determined [8]. Other Λ0b decays with a charmonium meson in the final state, such as the Cabibbo-suppressed decay Λ0b → J/ψ pπ− [11], can use the Λ0b →J/ψpK− decay as a reference to measure their absolute branching fractions. The product of the Λ0b (B0) differential production cross-section and the branching fraction of the Λ0b → J/ψ pK− (B0 → J/ψK∗0) decay is measured as a function of pT and y, where K∗0 indicates the K∗(892)0 meson throughout the text. The physics models used by LHCb in Geant for hadronic interactions have been tested against experimental data from COMPAS [20], and good agreement was observed.∗
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