We measure the time dependence of the ratio of decay rates for the rare decay D{0}-->K{+}pi{-} to the Cabibbo-favored decay D{0}-->K{-}pi;{+}. A signal of 12.7x10;{3} D{0}-->K{+}pi{-} decays was obtained using the Collider Detector at Fermilab II detector at the Fermilab Tevatron with an integrated luminosity of 1.5 fb;{-1}. We measure the D0-D[over ]{0} mixing parameters (R_{D},y{'},x{'2}), and find that the data are inconsistent with the no-mixing hypothesis with a probability equivalent to 3.8 Gaussian standard deviations.

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We experimentally investigated the equilibrium conformation and dynamics of single DNA molecules in slitlike nanochannels. We measured the in-plane radius of gyration (R ) ), diffusivity (D), and longest relaxation time (τ) of λ-DNA (48.5 kbp) as functions of the slit height using fluorescence microscopy. Our results show that the in-plane radius of gyration increases monotonically with decreasing slit height, in contrast to results from Bonthuis et al. 15 but in agreement with our simulations and those of other groups. In strong confinement (slit height <100 nm), the scaling of D, τ, and R ) with slit height does not show an evident change, suggesting that the transition from the de Gennes regime to the Odijk regime is gradual and broad.

We report the first measurements of inclusive W and Z boson cross sections times the corresponding leptonic branching ratios for pp collisions at √ s = 1.96 TeV based on the decays of the W and Z bosons into electrons and muons. The data were recorded with the CDF II detector at the Fermilab 4Tevatron and correspond to an integrated luminosity of 72.0 ± 4.3 pb −1 . We test e-µ lepton universality in W decays by measuring the ratio of the W → µν to W → eν cross sections and determine a value of 0.991 ± 0.004(stat.) ± 0.011(syst.) for the ratio of W −ℓ−ν couplings (gµ/ge). Since there is no sign of non-universality, we combine our cross section measurements in the different lepton decay modes and obtain σW ×Br(pp → W → ℓν) = 2.749 ± 0.010(stat.) ± 0.053(syst.) ± 0.165(lum.) nb and σ γ * /Z × Br(pp → γ * /Z → ℓℓ) = 254.9 ± 3.3(stat.) ± 4.6(syst.) ± 15.2(lum.) pb for dilepton pairs in the mass range between 66 GeV/c 2 and 116 GeV/c 2 . We compute the ratio R of the W → ℓν to Z → ℓℓ cross sections taking all correlations among channels into account and obtain R = 10.84 ± 0.15(stat.) ± 0.14(syst.) including a correction for the virtual photon exchange component in our measured γ * /Z → ℓℓ cross section. Based on the measured value of R, we extract values for the W leptonic branching ratio, Br(W → ℓν) = 0.1082 ± 0.0022; the total width of the W boson, Γ(W ) = 2092 ± 42 MeV; and the ratio of W and Z boson total widths, Γ(W )/Γ(Z) = 0.838 ± 0.017. In addition, we use our extracted value of Γ(W ) whose value depends on various electroweak parameters and certain CKM matrix elements to constrain the Vcs CKM matrix element, |Vcs| = 0.976± 0.030.

We present a new measurement of the inclusive and differential production cross sections of J= mesons and b hadrons in proton-antiproton collisions at s p 1960 GeV. The data correspond to an integrated luminosity of 39:7 pb ÿ1 collected by the CDF run II detector. We find the integrated cross section for inclusive J= production for all transverse momenta from 0 to 20 GeV=c in the rapidity range jyj < 0:6 to be 4:08 0:02stat 0:36 ÿ0:33 syst b. We separate the fraction of J= events from the decay of the long-lived b hadrons using the lifetime distribution in all events with p T J= > 1:25 GeV=c. We find the total cross section for b hadrons, including both hadrons and antihadrons, decaying to J= with transverse momenta greater than 1:25 GeV=c in the rapidity range jyJ= j < 0:6 is 0:330 0:005stat 0:036 ÿ0:033 syst b. Using a Monte Carlo simulation of the decay kinematics of b hadrons to all final states containing a J= , we extract the first measurement of the total single b-hadron cross section down to zero transverse momentum at s p 1960 GeV. We find the total single b-hadron cross section integrated over all transverse momenta for b hadrons in the rapidity range jyj < 0:6 to be 17:6 0:4stat 2:5 ÿ2:3 syst b.