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

Abstract

The relative production rate of B[superscript 0][subscript s] and B[superscript 0] mesons is determined with the hadronic decays B[superscript 0][subscript s]→D[superscript −][subscript s]π[superscript +] and B[superscript 0] → D[superscript −]K[superscript +]. The measurement uses data corresponding to 1.0 fb[superscript −1] of pp collisions at a centre-of-mass energy of s√=7s=7 TeV recorded in the forward region with the LHCb experiment. The ratio of production rates, f[subscript s]/f[subscript 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[subscript s]/f[subscript d] = 0.256 ± 0.020. The dependence of f[subscript s]/f[subscript d] on the transverse momentum and pseudorapidity of the B meson is determined using the decays B[superscript 0][subscript s]→D[superscript −][subscript s]π[superscript +] and B[superscript 0] → D[superscript −]π[superscript +]. 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[superscript 0] → D[superscript −]K[superscript +] and B[superscript 0] → D[superscript −]π[superscript +] is measured to be 0.0822 ± 0.0011 (stat) ± 0.0025 (syst).