Measurement of b hadron production fractions in 7 TeV pp collisions

Measurements of b hadron production ratios in proton-proton collisions at a center-of-mass energy of 7 TeV with an integrated luminosity of 3  pb-1 are presented. We study the ratios of strange B meson to light B meson production fs/(fu+fd) and Λb0 baryon to light B meson production fΛb/(fu+fd) as a function of the charmed hadron-muon pair transverse momentum pT and the b hadron pseudorapidity η, for pT between 0 and 14 GeV and η between 2 and 5. We find that fs/(fu+fd) is consistent with being independent of pT and η, and we determine fs/(fu+fd)=0.134±0.004-0.010+0.011, where the first error is statistical and the second systematic. The corresponding ratio fΛb/(fu+fd) is found to be dependent upon the transverse momentum of the charmed hadron-muon pair, fΛb/(fu+fd)=(0.404±0.017(stat)±0.027(syst)±0.105(Br))×[1-(0.031±0.004(stat)±0.003(syst))×pT(GeV)], where Br reflects an absolute scale uncertainty due to the poorly known branching fraction B(Λc+→pK-π+). We extract the ratio of strange B meson to light neutral B meson production fs/fd by averaging the result reported here with two previous measurements derived from the relative abundances of B̅ s0→Ds+π- to B̅ 0→D+K- and B̅ 0→D+π-. We obtain fs/fd=0.267-0.020+0.021.