Measurement of the Forward-Backward Asymmetry in the Production of $B^{\pm }$ Mesons in $p\overline{p}$ Collisions at $\sqrt{s}=1.96\mathrm{TeV}$

We present a measurement of the forward-backward asymmetry in the production of $B^{\pm }$ mesons, $A_{\mathrm{FB}}(B^{\pm })$, using $B^{\pm }\to J/\psi K^{\pm }$ decays in $10.4{\mathrm{fb}}^{-1}$ of $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ collected by the D0 experiment during Run II of the Tevatron collider. A nonzero asymmetry would indicate a preference for a particular flavor, i.e., $b$ quark or $\overline{b}$ antiquark, to be produced in the direction of the proton beam. We extract $A_{\mathrm{FB}}(B^{\pm })$ from a maximum likelihood fit to the difference between the numbers of forward- and backward-produced $B^{\pm }$ mesons. We measure an asymmetry consistent with zero: $A_{\mathrm{FB}}(B^{\pm })=[-0.24\pm 0.41(\mathrm{stat})\pm 0.19(\mathrm{syst})]\%$.

Figure 1

Invariant mass $M(J/\psi K)$ of ($\mathrm{forward}+\mathrm{backward}$) events with fitted distributions. The lower pane shows the residuals.

Figure 2

Invariant mass $M(J/\psi K)$ of ($\mathrm{forward}-\mathrm{backward}$) events with fitted distributions which include the asymmetry parameters $A_i$.

Figure 3

Comparison of $A_{\mathrm{FB}}(B^{\pm })$ and $A_{\mathrm{FB}}^{\mathrm{SM}}(B^{\pm })$ in bins of (a) $|{\eta }_B|$ and (b) $p_T(B)$. Data points and MC bands include statistical uncertainties convoluted with systematic uncertainties.