143 research outputs found

    First evidence for WW and WZ diboson production with semi-leptonic decays at a Hadron Collider

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    Presented is a measurement of the simultaneous production of a W{sup {+-}} boson in association with a second weak boson (W{sup {+-}} or Z{sup 0}) in p{bar p} collisions at {radical}s = 1.96 TeV. Events are consider with one electron or one muon, missing transverse energy, and at least two hadronic jets. The data were collected by the D0 detector in Run IIa of the Tevatron accelerator and correspond to 1.07 fb{sup -1} of integrated luminosity for each of the two channels (WW/WZ {yields} e{nu}q{bar q} and WW/WZ {yields} {mu}{nu}q{bar q}). The cross section for WW + WZ production is measured to be 20.2 {+-} 2.5(stat) {+-} 3.6(sys) {+-} 1.2(lum) pb with a Gaussian significance of 4.4 standard deviations above the background-only scenario. This measurement is consistent with the Standard Model prediction and represents the first direct evidence for WW and WZ production with semi-leptonic decays at a hadron collider

    Evidence for Zc±(3900)Z_c^{\pm}(3900) in semi-inclusive decays of bb-flavored hadrons

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    International audienceWe present evidence for the exotic charged charmoniumlike state Zc±(3900) decaying to J/ψπ± in semi-inclusive weak decays of b-flavored hadrons. The signal is correlated with a parent J/ψπ+π- system in the invariant-mass range 4.2–4.7 GeV that would include the exotic structure Y(4260). The study is based on 10.4  fb−1 of pp¯ collision data collected by the D0 experiment at the Fermilab Tevatron collider

    Measurement of the forward-backward asymmetry in Λb0\Lambda_b^0 and Λb0\overline \Lambda_b^0 baryon production in ppp \overline p collisions at s=1.96\sqrt s =1.96 TeV

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    We measure the forward-backward asymmetry in the production of Λb0\Lambda_b^0 and Λb0\overline \Lambda_b^0 baryons as a function of rapidity in ppp \overline p collisions at s=1.96\sqrt s =1.96 TeV using 10.410.4 fb1^{-1} of data collected with the D0 detector at the Fermilab Tevatron collider. The asymmetry is determined by the preference of Λb0\Lambda_b^0 or Λb0\overline \Lambda_b^0 particles to be produced in the direction of the beam protons or antiprotons, respectively. The measured asymmetry integrated over rapidity yy in the range 0.1<y<20.1<|y|<2 is A=0.04±0.07(stat)±0.02(syst)A=0.04 \pm 0.07 {\rm (stat)} \pm 0.02 {\rm (syst)}

    Measurement of the forward-backward asymmetry in the production of B±B^{\pm} mesons in ppˉp\bar{p} collisions at s\sqrt{s} = 1.96 TeV

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    We present a measurement of the forward-backward asymmetry in the production of B±B^{\pm} mesons, AFB(B±)A_{\rm FB}(B^{\pm}), using B±J/ψK±B^{\pm} \rightarrow J/\psi K^{\pm} decays in 10.4 fb1{\rm fb}^{-1} of ppˉp\bar{p} collisions at s=1.96\sqrt{s} = 1.96 TeV collected by the D0 experiment during Run II of the Tevatron collider. A non-zero asymmetry would indicate a preference for a particular flavor, i.e., bb quark or bˉ\bar{b} anti-quark, to be produced in the direction of the proton beam. We extract AFB(B±)A_{\rm FB}(B^{\pm}) from a maximum likelihood fit to the difference between forward- and backward-produced B±B^{\pm} mesons. We measure an asymmetry consistent with zero: AFB(B±)A_{\rm FB}(B^{\pm}) = [-0.24 ±\pm 0.41 (stat) ±\pm 0.19 (syst)]%
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