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 f(s)/(f(u) + f(d)) and Lambda(0)(b) baryon to light B meson production f(Lambda b)/(f(u) + f(d)) as a function of the charmed hadron-muon pair transverse momentum p(T) and the b hadron pseudorapidity eta, for p(T) between 0 and 14 GeV and eta between 2 and 5. We find that f(s)/(f(u) + f(d)) is consistent with being independent of p(T) and eta, 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(Lambda b)/(f(u) + f(d)) is found to be dependent upon the transverse momentum of the charmed hadron-muon pair, f(Lambda b)/(f(u) + f(d)) = (0.404 +/- 0.017(stat)+/- 0.027(syst)+/-0.105(Br)) x [1-(0.031 +/- 0.004(sta)+/-0.003(syst) x p(T)(GeV)], where Br reflects an absolute scale uncertainty due to the poorly known branching fraction B(Lambda(+)(c) -> pK(-)pi(+). 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 (B) over bar (0)(s) -> D-s(+) pi(-) to (B) over bar (0) -> D+K- and (B) over bar (0) -> D+ pi(-). We obtain f(s)/f(d) = 0.267(-0.020)(+0.021).