CDF Collaboration(Aaltonen, T. et al), & Cabrera, S. (2010). Studying the underlying event in Drell-Yan and high transverse momentum jet production at the Tevatron. Phys. Rev. D, 82(3), 034001–21pp.
Abstract: We study the underlying event in proton-antiproton collisions by examining the behavior of charged particles produced in association with a large transverse momentum jet (similar to 2: 2 fb(-1)) or with a Drell-Yan lepton pair (similar to 2.7 fb(-1)) in the Z-boson mass region [70 < M(pair) < 110 GeV/c(2)] as measured by CDF at 1.96 TeV center-of-mass energy. We use the direction of the lepton pair or the leading jet in each event to define regions of eta-phi space that are sensitive to the modeling of the underlying event. The data are corrected to the particle level to remove detector effects and are then compared with several QCD Monte Carlo models.
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CDF Collaboration(Aaltonen, T. et al), & Cabrera, S. (2011). Measurement of the B- lifetime using a simulation free approach for trigger bias correction. Phys. Rev. D, 83(3), 032008–30pp.
Abstract: The collection of a large number of B-hadron decays to hadronic final states at the CDF II Detector is possible due to the presence of a trigger that selects events based on track impact parameters. However, the nature of the selection requirements of the trigger introduces a large bias in the observed proper-decay-time distribution. A lifetime measurement must correct for this bias, and the conventional approach has been to use a Monte Carlo simulation. The leading sources of systematic uncertainty in the conventional approach are due to differences between the data and the Monte Carlo simulation. In this paper, we present an analytic method for bias correction without using simulation, thereby removing any uncertainty due to the differences between data and simulation. This method is presented in the form of a measurement of the lifetime of the B- using the mode B- -> D-0 pi(-). The B- lifetime is measured as tau(-)(B) = 1.663 +/- 0.023 +/- 0.015 ps, where the first uncertainty is statistical and the second systematic. This new method results in a smaller systematic uncertainty in comparison to methods that use simulation to correct for the trigger bias.
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CDF Collaboration(Aaltonen, T. et al), Cabrera, S., & Cuenca Almenar, C. (2010). Measurements of the top-quark mass using charged particle tracking. Phys. Rev. D, 81(3), 032002–21pp.
Abstract: We present three measurements of the top-quark mass in the lepton plus jets channel with approximately 1.9 fb(-1) of integrated luminosity collected with the CDF II detector using quantities with minimal dependence on the jet energy scale. One measurement exploits the transverse decay length of b-tagged jets to determine a top-quark mass of 166.9(-8.5)(+9.5)(stat) +/- 2.9(syst) GeV/c(2), and another the transverse momentum of electrons and muons from W-boson decays to determine a top-quark mass of 173.5(-8.9)(+8.8)(stat) +/- 3.8(syst) GeV/c(2). These quantities are combined in a third, simultaneous mass measurement to determine a top-quark mass of 170.7 +/- 6.3(stat) +/- 2.6(syst) GeV/c(2) .
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CDF Collaboration(Aaltonen, T. et al), & Cabrera, S. (2011). Search for a Very Light CP-Odd Higgs Boson in Top Quark Decays from p p-bar Collisions at sqrt(s)=1.96 TeV. Phys. Rev. Lett., 107(3), 031801–8pp.
Abstract: We present the results of a search for a very light CP-odd Higgs boson a(1)(0) originating from top quark decays t -> H(+/-)b -> W(+/-(*)) a(1)(0)b, and subsequently decaying into tau(+)tau(-). Using a data sample corresponding to an integrated luminosity of 2.7 fb(-1) collected by the CDF II detector in p (p) over bar collisions at 1.96 TeV, we perform a search for events containing a lepton, three or more jets, and an additional isolated track with transverse momentum in the range 3 to 20 GeV/c. Observed events are consistent with background sources, and 95% C.L. limits are set on the branching ratio of t -> H(+/-)b for various masses of H(+/-) and a(1)(0).
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CDF Collaboration(Aaltonen, T. et al), & Cabrera, S. (2010). Measurements of branching fraction ratios and CP asymmetries in B-+/- -> DCPK +/- decays in hadron collisions. Phys. Rev. D, 81(3), 031105–9pp.
Abstract: We reconstruct B-+/- -> DK +/- decays in a data sample collected by the CDF II detector at the Tevatron collider corresponding to 1 fb(-1) of integrated luminosity. We select decay modes where the D meson decays to either K-pi(+) (flavor eigenstate) or K-K+, pi(-)pi(+) (CP-even eigenstates), and measure the direct CP asymmetry A(CP+) = 0.39 +/- 0.17(stat) +/- 0.04(syst), and the double ratio of CP-even to flavor eigenstate branching fractions RCP+ = 1.30 +/- 0.24(stat) +/- 0.12(syst). These measurements will improve the determination of the Cabibbo-Kobayashi-Maskawa angle gamma. They are performed here for the first time using data from hadron collisions.
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