Measurement of b hadron production fractions in 7 TeV pp collisions

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Measurements of $b$ hadron production ratios in proton-proton collisions at a center-of-mass energy of 7 TeV with an integrated luminosity of $3\text{ }\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$ are presented. We study the ratios of strange $B$ meson to light $B$ meson production ${f}_{s}/({f}_{u}+{f}_{d})$ and ${\ensuremath{\Lambda}}_{b}^{0}$ baryon to light $B$ meson production ${f}_{{\ensuremath{\Lambda}}_{b}}/({f}_{u}+{f}_{d})$ as a function of the charmed hadron-muon pair transverse momentum ${p}_{\mathrm{T}}$ and the $b$ hadron pseudorapidity $\ensuremath{\eta}$, for ${p}_{\mathrm{T}}$ between 0 and 14 GeV and $\ensuremath{\eta}$ between 2 and 5. We find that ${f}_{s}/({f}_{u}+{f}_{d})$ is consistent with being independent of ${p}_{\mathrm{T}}$ and $\ensuremath{\eta}$, and we determine ${f}_{s}/({f}_{u}+{f}_{d})=0.134\ifmmode\pm\else\textpm\fi{}{0.004}_{\ensuremath{-}0.010}^{+0.011}$, where the first error is statistical and the second systematic. The corresponding ratio ${f}_{{\ensuremath{\Lambda}}_{b}}/({f}_{u}+{f}_{d})$ is found to be dependent upon the transverse momentum of the charmed hadron-muon pair, ${f}_{{\ensuremath{\Lambda}}_{b}}/({f}_{u}+{f}_{d})=(0.404\ifmmode\pm\else\textpm\fi{}0.017(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.027(\mathrm{syst})\ifmmode\pm\else\textpm\fi{}0.105(\mathrm{Br}))\ifmmode\times\else\texttimes\fi{}[1\ensuremath{-}(0.031\ifmmode\pm\else\textpm\fi{}0.004(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.003(\mathrm{syst}))\ifmmode\times\else\texttimes\fi{}{p}_{\mathrm{T}}(\mathrm{GeV})]$, where Br reflects an absolute scale uncertainty due to the poorly known branching fraction $\mathcal{B}({\ensuremath{\Lambda}}_{c}^{+}\ensuremath{\rightarrow}p{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+})$. 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 ${\overline{B}}_{s}^{0}\ensuremath{\rightarrow}{D}_{s}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ to ${\overline{B}}^{0}\ensuremath{\rightarrow}{D}^{+}{K}^{\ensuremath{-}}$ and ${\overline{B}}^{0}\ensuremath{\rightarrow}{D}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$. We obtain ${f}_{s}/{f}_{d}={0.267}_{\ensuremath{-}0.020}^{+0.021}$.

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