We report a study of multi-muon events produced at the Fermilab Tevatron collider and recorded by the CDF II detector. In a data set acquired with a dedicated dimuon trigger and corresponding to an integrated luminosity of 2100 pb −1 , we isolate a significant sample of events in which at least one of the muon candidates is produced outside of the beam pipe of radius 1.5 cm. The production cross section and kinematics of events in which both muon candidates are produced inside the beam pipe are successfully modeled by known QCD processes which include heavy flavor production. In contrast, we are presently unable to fully account for the number and properties of the remaining events, in which at least one muon candidate is produced outside of the beam pipe, in terms of the same understanding of the CDF II detector, trigger, and event reconstruction. Several topological and kinematic properties of these events are presented in this paper. These events offer a plausible resolution to long-standing inconsistencies related to b b production and decay.

We present the results of the first hadron collider search for heavy, long-lived neutralinos that decay via χ 0 1 → γ G in gauge-mediated supersymmetry breaking models. Using an integrated luminosity of 570±34 pb −1 of pp collisions at √ s = 1.96 TeV, we select γ+jet+missing transverse energy candidate events based on the arrival time of a high-energy photon at the electromagnetic calorimeter as measured with a timing system that was recently installed on the CDF II detector. We find 2 events, consistent with the background estimate of 1.3±0.7 events. While our search strategy does not rely on model-specific dynamics, we set cross section limits and place the world-best 95% C.L. lower limit on the χ

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We present a new measurement of the B + meson differential cross section dσ/dp T at √ s = 1960GeV. The data correspond to an integrated luminosity of 739 pb −1 collected with the upgraded CDF detector (CDF II) at the Fermilab Tevatron collider. B + candidates are reconstructed through the decay B + → J/ψ K + , with J/ψ → µ + µ − . The integrated cross section for producing B + mesons with p T ≥ 6 GeV/c and |y| ≤ 1 is measured to be 2.78 ± 0.24 µb.

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