Average f_s/f_d b-hadron production fraction for 7TeV pp collisions

We extract the ratio of strange $B$ meson to light neutral $B$ meson production $f_s/f_d$ by averaging three measurements performed in proton-proton collisions at a centre-of-mass energy of 7 TeV. They include a determination using semileptonic decays of the $b$-hadrons, identified by the detection of a muon and a charmed hadron, and two measurements derived from the relative abundances of $B_s^0\rightarrow D_s^- \pi^+$ to $B^0\rightarrow D^-K^+$ and $B^0\rightarrow D^-\pi^+$. We obtain $f_s/f_d=0.267^{+0.021}_{-0.020}$