Measurement of the fragmentation fraction ratio fs/fdand its dependence on B meson kinematics

The relative production rate of B ⁰ _sand B ⁰mesons is determined with the hadronic decays B ⁰ _s→ D ⁻ _sπ ⁺and B ⁰→ D ⁻K ⁺. The measurement uses data corresponding to 1.0 fb ⁻¹of pp collisions at a centre-of-mass energy of √s = 7TeV recorded in the forward region with the LHCb experiment. The ratio of production rates, f _s/f _d, is measured to be 0.238 ± 0.004 ± 0.015 ± 0.021, where the first uncertainty is statistical, the second systematic, and the third theoretical. This is combined with a previous LHCb measurement to obtain f _s/f _d= 0.256 ±0.020. The dependence of f _s/f _don the transverse momentum and pseudorapidity of the B meson is determined using the decays B ⁰ _s→ D ⁻ _sπ ⁺and B ⁰→ D ⁻π ⁺. There is evidence for a decrease with increasing transverse momentum, whereas the ratio remains constant as a function of pseudorapidity. In addition, the ratio of branching fractions of the decays B ⁰→ D ⁻K ⁺and B ⁰→ D ⁻π ⁺is measured to be 0.0822 ± 0.0011 (stat) ± 0.0025 (syst).