Measurement of the Bs0-Bs0 oscillation frequency.
Phys Rev Lett 97:6 (2006) 062003
Abstract:
We present the first precise measurement of the Bs0-Bs0 oscillation frequency Deltams. We use 1 fb-1 of data from pp collisions at sqrts=1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. The sample contains signals of 3600 fully reconstructed hadronic Bs decays and 37,000 partially reconstructed semileptonic Bs decays. We measure the probability as a function of proper decay time that the Bs decays with the same, or opposite, flavor as the flavor at production, and we find a signal consistent with Bs0-Bs0 oscillations. The probability that random fluctuations could produce a comparable signal is 0.2%. Under the hypothesis that the signal is due to Bs0-Bs0 oscillations, we measure Deltams=17.31(-0.18)+0.33(stat)+/-0.07(syst) ps-1 and determine |Vtd/Vts|=0.208(-0.002)+0.001(expt)-0.006(+0.008)(theor).Measurement of the b jet cross section in events with a Z boson in pp¯ collisions at s=1.96 TeV
Physical Review D American Physical Society (APS) 74:3 (2006) 032008
Abstract:
A measurement of the inclusive bottom jet cross section is presented for events containing a Z boson in pp¯ collisions at s=1.96 TeV using the Collider Detector at Fermilab. Z bosons are identified in their electron and muon decay modes, and b jets with ET>20 GeV and |η|<1.5 are identified by reconstructing a secondary decay vertex. The measurement is based on an integrated luminosity of about 330 pb-1. A cross section times branching ratio of σ(Z+b jets)×B(Z→ℓ+ℓ-)=0.93±0.36 pb is found, where B(Z→ℓ+ℓ-) is the branching ratio of the Z boson or γ* into a single flavor dilepton pair (e or μ) in the mass range between 66 and 116 GeV/c2. The ratio of b jets to the total number of jets of any flavor in the Z sample, within the same kinematic range as the b jets, is 2.36±0.92%. Here, the uncertainties are the quadratic sum of statistical and systematic uncertainties. Predictions made with next-to-leading order QCD agree, within experimental and theoretical uncertainties, with these measurements.Measurement of the ratio of branching fractions B(D0→K+π-)/B(D0→K-π+) using the CDF II detector
Physical Review D American Physical Society (APS) 74:3 (2006) 031109
Abstract:
We present a measurement of RB, the ratio of the branching fraction for the rare decay D0→K+π- to that for the Cabibbo-favored decay D0→K-π+. Charge-conjugate decays are implicitly included. A signal of 2005±104 events for the decay D0→K+π- is obtained using the CDF II detector at the Fermilab Tevatron collider. The data set corresponds to an integrated luminosity of 0.35 fb-1 produced in p¯p collisions at s=1.96 TeV. Assuming no mixing, we find RB=[4.05±0.21(stat)±0.11(syst)]×10-3. This measurement is consistent with the world average, and comparable in accuracy with the best measurements from other experiments.Top quark mass measurement from dilepton events at CDF II with the matrix-element method
Physical Review D American Physical Society (APS) 74:3 (2006) 032009
Abstract:
We describe a measurement of the top quark mass using events with two charged leptons collected by the CDF II detector from pp¯ collisions with s=1.96 TeV at the Fermilab Tevatron. The likelihood in top quark mass is calculated for each event by convoluting the leading order matrix element describing qq¯→tt¯→bℓνℓb¯ℓ′νℓ′ with detector resolution functions. The presence of background events in the data sample is modeled using similar calculations involving the matrix elements for major background processes. In a data sample with integrated luminosity of 340 pb-1, we observe 33 candidate events and measure Mtop=165.2±6.1(stat.)±3.4(syst.) GeV/c2. This measurement represents the first application of this method to events with two charged leptons and is the most precise single measurement of the top quark mass in this channel.A Study of Laser System Requirements for Application in Beam Diagnostics and Polarimetry at the ILC
CERN (2006)