Measurement of b hadron production fractions in 7 TeV pp collisions

Abstract

Measurements of b hadron production ratios in proton-proton collisions at a center-of-mass energy of 7 TeV with an integrated luminosity of 3 pb − 1 are presented. We study the ratios of strange B meson to light B meson production f s / ( f u + f d ) and Λ 0 b baryon to light B meson production f Λ b / ( f u + f d ) as a function of the charmed hadron-muon pair transverse momentum p T and the b hadron pseudorapidity η , for p T between 0 and 14 GeV and η between 2 and 5. We find that f s / ( f u + f d ) is consistent with being independent of p T and η , and we determine f s / ( f u + f d ) = 0.134 ± 0.004 + 0.011 − 0.010 , where the first error is statistical and the second systematic. The corresponding ratio f Λ b / ( f u + f d ) is found to be dependent upon the transverse momentum of the charmed hadron-muon pair, f Λ b / ( f u + f d ) = ( 0.404 ± 0.017 ( stat ) ± 0.027 ( syst ) ± 0.105 ( Br ) ) × [ 1 − ( 0.031 ± 0.004 ( stat ) ± 0.003 ( syst ) ) × p T ( GeV ) ] , where Br reflects an absolute scale uncertainty due to the poorly known branching fraction B ( Λ + c → p K − π + ) . We extract the ratio of strange B meson to light neutral B meson production f s / f d by averaging the result reported here with two previous measurements derived from the relative abundances of ¯¯¯ B 0 s → D + s π − to ¯¯¯ B 0 → D + K − and ¯¯¯ B 0 → D + π − . We obtain f s / f d = 0.267 + 0.021 − 0.020 .