Zhaoou Yu

The studies of bottom quark-antiquark production in proton-antiproton collisions play an important role in testing perturbative QCD. Measuring the mixing parameter of B mesons imposes constraints on the quark mixing (CKM) matrix and enhances the understanding of the Standard Model. Multi-GeV pp¯ colliders produce a significant amount of bb¯ pairs and thus enable studies in both of these fields.

This thesis presents results of the  bb¯ production cross section from pp¯ collisions at √s = 1.8 TeV and the time-integrated average BB¯ mixing parameter (χ¯)  using high-mass dimuon data collected by CDF during its Run IB. There is a high concentration of muon pairs from inclusive semileptonic B decays in this data set. We take advantage of the long lifetime property of B hadrons and isolate the muons from B decays by studying the displacement of the muon pair trajectories. We use an Unbinned Maximum Likelihood Fitting method to fit the two dimensional impact parameter distribution for dimuons and thus obtain the fraction of dimuons that are from bb¯. With this bb¯ fraction and accounting for the detector acceptance and efficiencies, we obtain the bb¯ production cross section as a function of the minimum transverse momenta of the b quarks. We also obtain the B mixing parameter by comparing the numbers of like-sign bb¯ dimuons and opposite-sign bb¯ dimuons.

The measured bb¯ production cross sections are systematically higher than the Next-To-Leading-Order QCD predictions but are consistent with the CDF Run IA results [1]. The measured average B meson mixing parameter is 0.153 ± .019 and is within two standard deviations of the world average value.