First measurement of the forward-backward asymmetry in bottom-quark pair production at high mass

We measure the particle-level forward-backward production asymmetry in $b\overline{b}$ pairs with masses (${m}_{b\overline{b}}$) larger than $150\text{ }\text{ }\mathrm{GeV}/{c}^{2}$, using events with hadronic jets and employing jet charge to distinguish $b$ from $\overline{b}$. The measurement uses $9.5\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of $p\overline{p}$ collisions at a center-of-mass energy of 1.96 TeV recorded by the CDF II detector. The asymmetry as a function of ${m}_{b\overline{b}}$ is consistent with zero, as well as with the predictions of the standard model. The measurement disfavors a simple model including an axigluon with a mass of $200\text{ }\text{ }\mathrm{GeV}/{c}^{2}$, whereas a model containing a heavier $345\text{ }\text{ }\mathrm{GeV}/{c}^{2}$ axigluon is not excluded.