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 3pb ^-1 are presented. We study the ratios of strange B meson to light B meson production f _s/(f _u+f _d) and Λb0 baryon to light B meson production f _Λb/(f _u+f _d) as a function of the charmed hadron-muon pair transverse momentum p _T and the b hadron pseudorapidity η, for p _T between 0 and 14 GeV and η between 2 and 5. We find that f _s/(f _u+f _d) is consistent with being independent of p _T and η, and we determine f _s/(f _u+f _d)=0.134±0.004-0.010+0.011, where the first error is statistical and the second systematic. The corresponding ratio f _Λb/(f _u+f _d) is found to be dependent upon the transverse momentum of the charmed hadron-muon pair, f _Λb/(f _u+f _d)=(0.404±0. 017(stat)±0.027(syst)±0.105(Br))×[1-(0.031±0. 004(stat)±0.003(syst))×p _T(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 f _s/f _d by averaging the result reported here with two previous measurements derived from the relative abundances of B̄s0→Ds+π ^- to B ^̄0→D ⁺K ^- and B ^̄0→ D ⁺π ^-. We obtain f _s/f _d=0.267-0. 020+0.021.