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

Abstract

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 0D 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 0D 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 0D K + and B 0D π+ is measured to be 0.0822 ± 0.0011 (stat) ± 0.0025 (syst).

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