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

Abstract

We measure the particle-level forward-backward production asymmetry in b¯b pairs with masses (mb¯b) larger than 150 GeV/c2, using events with hadronic jets and employing jet charge to distinguish b from ¯b. The measurement uses 9.5 fb−1 of p¯p collisions at a center-of-mass energy of 1.96 TeV recorded by the CDF II detector. The asymmetry as a function of mb¯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 GeV/c2, whereas a model containing a heavier 345 GeV/c2 axigluon is not excluded.