Measurements of $b$ hadron production ratios in proton-proton collisions at a center-of-mass energy of 7 TeV with an integrated luminosity of $3{\mathrm{pb}}^{-1}$ are presented. We study the ratios of strange $B$ meson to light $B$ meson production $f_s/(f_u+f_d)$ and ${\Lambda }_b^0$ baryon to light $B$ meson production $f_{{\Lambda }_b}/(f_u+f_d)$ as a function of the charmed hadron-muon pair transverse momentum $p_{\mathrm{T}}$ and the $b$ hadron pseudorapidity $\eta$, for $p_{\mathrm{T}}$ 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 $p_{\mathrm{T}}$ and $\eta$, and we determine $f_s/(f_u+f_d)=0.134\pm {0.004}_{-0.010}^{+0.011}$, 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, $f_{{\Lambda }_b}/(f_u+f_d)=(0.404\pm 0.017(\mathrm{stat})\pm 0.027(\mathrm{syst})\pm 0.105(\mathrm{Br}))\times [1-(0.031\pm 0.004(\mathrm{stat})\pm 0.003(\mathrm{syst}))\times p_{\mathrm{T}}(\mathrm{GeV})]$, where Br reflects an absolute scale uncertainty due to the poorly known branching fraction $\mathcal{B}({\Lambda }_c^{+}\to p{K}^{-}{\pi }^{+})$. 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 ${\overline{B}}_s^0\to D_s^{+}{\pi }^{-}$ to ${\overline{B}}^0\to D^{+}{K}^{-}$ and ${\overline{B}}^0\to D^{+}{\pi }^{-}$. We obtain $f_s/f_d={0.267}_{-0.020}^{+0.021}$.

• Received 9 November 2011

DOI:https://doi.org/10.1103/PhysRevD.85.032008

This article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

© 2012 CERN, for the LHCb Collaboration