paper

Measurement of b hadron production fractions in 7 TeV pp collisions

arXiv:1111.2357 · doi:10.1103/PhysRevD.85.032008

Abstract

Measurements of $b$ hadron production ratios in proton-proton collisions at a centre-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 $I^_{b}^{0}$ baryon to light $B$ meson production $f_{I^_{b}} / (f_{u} + f_{d})$ as a function of the charmed hadron-muon pair transverse momentum $p_{T}$ and the $b$ hadron pseudorapidity $I^\cdot$ , for $p_{T}$ between 0 and 14 GeV and $I^\cdot$ between 2 and 5. We find that $f_{s} / (f_{u} + f_{d})$ is consistent with being independent of $p_{T}$ and $I^\cdot$ , and we determine $f_{s} / (f_{u} + f_{d})$ = 0.134 $\pm$ 0.004 $_{- 0.010}^{+ 0.011}$ , where the first error is statistical and the second systematic. The corresponding ratio $f_{I^_{b}} / (f_{u} + f_{d})$ is found to be dependent upon the transverse momentum of the charmed hadron-muon pair, $f_{I^_{b}} / (f_{u} + f_{d}) = (0.404 \pm 0.017 (s t a t) \pm 0.027 (sy s t) \pm 0.105 (B r)) \times [1 - (0.031 \pm 0.004 (s t a t) \pm 0.003 (sy s t)) \times p_{T} (G e V)]$ , where Br reflects an absolute scale uncertainty due to the poorly known branching fraction Br(Î_c^+ \to pK^-Ï^+) $. W ee x t r a c tt h er a t i oo f s t r an g e$ B $m eso n t o l i g h t n e u t r a l$ B $m eso n p r o d u c t i o n$ f_s/f_d $b y a v er a g in g t h er es u l t r e p or t e d h er e w i t h tw o p r e v i o u s m e a s u r e m e n t s d er i v e df r o m t h er e l a t i v e ab u n d an ceso f$ \bar{B}_s \to D_S^+ Ï^- $t o$ \bar{B}^0 \to D^+K^- $an d$ \bar{B}^0 \to D^+Ï^- $. W eo b t ain$ f_s/f_d=0.267^{+0.021}_{-0.020}$.

28 pages, 12 figures, version accepted for publication in Physical Review D, few more detailed explanations on analysis methods added