Measurement of the fragmentation fraction ratio f s /f d and its dependence on B meson kinematics

A bstract The relative production rate of $ B_s^0 $ and B 0 mesons is determined with the hadronic decays $ B_s^0\to D_s^{-}{\pi^{+}} $ and B 0 → D − K + . The measurement uses data corresponding to 1.0 fb −1 of pp collisions at a centre-of-mass energy of $ \sqrt{s}=7 $ TeV 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 d on the transverse momentum and pseudorapidity of the B meson is determined using the decays $ B_s^0\to D_s^{-}{\pi^{+}} $ 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).