64 research outputs found

    Combined Forward-Backward Asymmetry Measurements in Top-Antitop Quark Production at the Tevatron

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    The CDF and D0 experiments at the Fermilab Tevatron have measured the asymmetry between yields of forward- and backward-produced top and antitop quarks based on their rapidity difference and the asymmetry between their decay leptons. These measurements use the full data sets collected in proton-antiproton collisions at a center-of-mass energy of s=1.96\sqrt s =1.96 TeV. We report the results of combinations of the inclusive asymmetries and their differential dependencies on relevant kinematic quantities. The combined inclusive asymmetry is AFBttˉ=0.128±0.025A_{\mathrm{FB}}^{t\bar{t}} = 0.128 \pm 0.025. The combined inclusive and differential asymmetries are consistent with recent standard model predictions

    Inclusive Production of the X(4140)X(4140) State in ppp \overline p Collisions at D0

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    We present a study of the inclusive production of the X(4140)X(4140) with the decay to the J/ψϕJ/\psi \phi final state in hadronic collisions. Based on 10.4 fb110.4~\rm{fb^{-1}} of ppp \overline p collision data collected by the D0 experiment at the Fermilab Tevatron collider, we report the first evidence for the prompt production of X(4140)X(4140) and find the fraction of X(4140)X(4140) events originating from bb hadrons to be fb=0.39±0.07(stat)±0.10(syst)f_b=0.39\pm 0.07 {\rm \thinspace (stat)} \pm 0.10 {\rm \thinspace (syst)} . The ratio of the non-prompt X(4140)X(4140) production rate to the Bs0B_s^0 yield in the same channel is R=0.19±0.05(stat)±0.07(syst)R=0.19 \pm 0.05 {\rm \thinspace (stat)} \pm 0.07 {\rm \thinspace (syst)}. The values of the mass M=4152.5±1.7(stat)5.4+6.2(syst)M=4152.5 \pm 1.7 (\rm {stat}) ^{+6.2}_{-5.4} {\rm \thinspace (syst)}~MeV and width Γ=16.3±5.6(stat)±11.4(syst)\Gamma=16.3 \pm 5.6 {\rm \thinspace (stat)} \pm 11.4 {\rm \thinspace (syst)}~MeV are consistent with previous measurements. 8 pages, 2 figue

    Search for Violation of CPTCPT and Lorentz invariance in Bs0{B_s^0} meson oscillations

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    We present the first search for CPT-violating effects in the mixing of Bs0{B_s^0} mesons using the full Run II data set with an integrated luminosity of 10.4 fb1^{-1} of proton-antiproton collisions collected using the D0 detector at the Fermilab Tevatron Collider. We measure the CPT-violating asymmetry in the decay Bs0μ±Ds±B_s^0 \to \mu^\pm D_s^\pm as a function of celestial direction and sidereal phase. We find no evidence for CPT-violating effects and place limits on the direction and magnitude of flavor-dependent CPT- and Lorentz-invariance violating coupling coefficients. We find 95\% confidence intervals of Δa<1.2×1012\Delta a_{\perp} < 1.2 \times 10^{-12} GeV and (0.8<ΔaT0.396ΔaZ<3.9)×1013(-0.8 < \Delta a_T - 0.396 \Delta a_Z < 3.9) \times 10^{-13} GeV

    Measurement of the Bs0B_s^0 lifetime in the flavor-specific decay channel Bs0Dsμ+νXB_s^0 \to D_s^- \mu^+\nu X

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    We present an updated measurement of the Bs0B_s^0 lifetime from the D0 collaboration using the semileptonic decays Bs0Dsμ+νXB_s^0\rightarrow D_s^-\mu^+\nu X, with DsϕπD_s^- \to \phi \pi^- and ϕK+K\phi \to K^+K^- (and the charge conjugate process). This measurement uses the full Tevatron Run II sample of proton-antiproton collisions at s=1.96\sqrt{s} = 1.96~TeV, comprising an integrated luminosity of 10.4~fb1^{-1}. We find a flavor-specific lifetime τfs(Bs0)=1.479±0.010(stat)±0.021(syst)ps\tau_{\mathrm{fs}}(B_s^0)=1.479\pm0.010\thinspace{\rm(stat)}\pm0.021\thinspace{\rm(syst)}\thinspace\rm{ps}. This technique is also used to determine the B0B^0 lifetime using the analogous B0Dμ+νXB^0\to D^-\mu^+\nu X decay with DϕπD^-\to\phi\pi^-, yielding τ(B0)=1.534±0.019(stat)±0.021(syst)ps\tau(B^0)=1.534\pm0.019\thinspace{\rm(stat)}\pm0.021\thinspace{\rm(syst)}\thinspace\rm{ps}. Both measurements are consistent with the current world averages, and the Bs0B_s^0 lifetime measurement is one of the most precise to date. Taking advantage of the cancellation of systematic uncertainties, we determine the lifetime ratio τfs(Bs0)/τ(B0)=0.964±0.013(stat)±0.007(syst)\tau_{\mathrm{fs}}(B_s^0)/\tau(B^0) = 0.964\pm0.013\thinspace{\rm(stat)}\pm0.007\thinspace{\rm(syst)}

    Measurement of the direct CPCP-violating parameter ACPA_{CP} in the decay D+Kπ+π+D^+ \to K^-\pi^+\pi^+

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    We measure the direct CP-violating parameter A_CP for the decay of the charged charm meson, D+ -> K-pi+pi+ (and charge conjugate), using the full 10.4 fb-1 sample of ppbar collisions at sqrt(s) = 1.96 TeV collected by the D0 detector at the Fermilab Tevatron collider. We extract the raw reconstructed charge asymmetry by fitting the invariant mass distributions for the sum and difference of charge-specific samples. This quantity is then corrected for detector-related asymmetries using data-driven methods and for possible physics asymmetries (from B -> D processes) using input from Monte Carlo simulation. We measure A_CP = [-0.16 +- 0.15 (stat.) +- 0.09 (syst.)]%, which is consistent with zero, as expected from the standard model prediction of CP conservation, and is the most precise measurement of this quantity to dateWe measure the direct CP-violating parameter ACP for the decay of the charged charm meson, D+→K-π+π+ (and charge conjugate), using the full 10.4  fb-1 sample of pp¯ collisions at s=1.96  TeV collected by the D0 detector at the Fermilab Tevatron collider. We extract the raw reconstructed charge asymmetry by fitting the invariant mass distributions for the sum and difference of charge-specific samples. This quantity is then corrected for detector-related asymmetries using data-driven methods and for possible physics asymmetries (from B→D processes) using input from Monte Carlo simulation. We measure ACP=[-0.16±0.15(stat)±0.09(syst)]%, which is consistent with zero, as expected from the standard model prediction of CP conservation, and is the most precise measurement of this quantity to date.We measure the direct CP-violating parameter A_CP for the decay of the charged charm meson, D+ -> K-pi+pi+ (and charge conjugate), using the full 10.4 fb-1 sample of ppbar collisions at sqrt(s) = 1.96 TeV collected by the D0 detector at the Fermilab Tevatron collider. We extract the raw reconstructed charge asymmetry by fitting the invariant mass distributions for the sum and difference of charge-specific samples. This quantity is then corrected for detector-related asymmetries using data-driven methods and for possible physics asymmetries (from B -> D processes) using input from Monte Carlo simulation. We measure A_CP = [-0.16 +- 0.15 (stat.) +- 0.09 (syst.)]%, which is consistent with zero, as expected from the standard model prediction of CP conservation, and is the most precise measurement of this quantity to dat
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