Measurement of the Forward-Backward Asymmetry in the Production of $B^{\pm}$ Mesons in $p\bar{p}$ Collisions.

Abstract

We present a measurement of the forward-backward asymmetry in the production of B± mesons, AFB(B±), using B± → J/ψK± decays in 10.4 fb -1 of p$\bar{p}$ collisions at √ s = 1.96 TeV collected by the DØ experiment during Run II of the Tevatron collider. A nonzero asymmetry would indicate a preference for a particular flavor, i.e., b quark or $\bar{b}$ antiquark, to be produced in the direction of the proton beam. We extract AFB(B±) from a maximum likelihood fit to the difference between the numbers of forward- and backward-produced B± mesons, using a boosted decision tree to reduce background. Corrections are made for reconstruction asymmetries of the decay products. We measure an asymmetry consistent with zero: AFB(B±) = [-0.24 ± 0.41 (stat)± 0.19 (syst)]%. The standard model estimate from next-to-leading-order Monte Carlo is ASM FB(B±) = [2.31 ± 0.34 (stat.)± 0.51 (syst.)]%. There is a difference of ≈ 3 standard deviations between this prediction and our result, which suggests that more rigorous determination of the standard model prediction is needed to interpret these results.

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