We study WW and WZ production with lvqq (l = e, mu) final states using data collected by the D0 detector at the Fermilab Tevatron Collider corresponding to 4.3 fb(-1) of integrated luminosity from p ...(p) over bar collisions at root s = 1.96 TeV. Assuming the ratio between the production cross sections sigma(WW) and sigma(WZ) as predicted by the standard model, we measure the total WV (V = W, Z) cross section to be sigma(WV) = 19.6(-3.0)(+3.2) pb and reject the background-only hypothesis at a level of 7.9 standard deviations. We also use b-jet discrimination to separate the WZ component from the dominant WW component. Simultaneously fitting WW and WZ contributions, we measure sigma(WW) = 15.9(-3.2)(+3.7) pb and sigma(WZ) = 3.3(-3.3)(+4.1) pb, which is consistent with the standard model predictions.
We present a search for Kaluza-Klein (KK) particles predicted by models with universal extra dimensions (UED) using a data set corresponding to an integrated luminosity of 7.3 fb(-1), collected by ...the D0 detector at a p (p) over bar center-of-mass energy of 1.96 TeV. The decay chain of KK particles can lead to a final state with two muons of the same charge. This signature is used to set a lower limit on the compactification scale of R-1 > 260 GeV in a minimal UED model.
We present a measurement of the W boson mass using data corresponding to 4.3 fb{sup -1} of integrated luminosity collected with the D0 detector during Run II at the Fermilab Tevatron p{bar p} ...collider. With a sample of 1677394 W {yields} e{nu} candidate events, we measure M{sub W} = 80.367 {+-} 0.026 GeV. This result is combined with an earlier D0 result determined using an independent Run II data sample, corresponding to 1 fb{sup -1} of integrated luminosity, to yield M{sub W} = 80.375 {+-} 0.023 GeV.
We report results from searches for neutral Higgs bosons produced in p{bar p} collisions recorded by the D0 experiment at the Fermilab Tevatron Collider. We study the production of inclusive neutral ...Higgs boson in the {tau}{tau} final state and in association with a b quark in the b{tau}{tau} and bbb final states. These results are combined to improve the sensitivity to the production of neutral Higgs bosons in the context of the minimal supersymmetric standard model (MSSM). The data are found to be consistent with expectation from background processes. Upper limits on MSSM Higgs boson production are set for Higgs boson masses ranging from 90 to 300 GeV. We exclude tan {beta} > 20-30 for Higgs boson masses below 180 GeV. These are the most stringent constraints on MSSM Higgs boson production in p{bar p} collisions.
Improved determination of the width of the top quark Adams, T.; Alexeev, G. D.; Åsman, B. ...
Physical review. D, Particles, fields, gravitation, and cosmology,
05/2012, Letnik:
85, Številka:
9
Journal Article
Odprti dostop
We present an improved determination of the total width of the top quark, Gammat, using 5.4 fb super(-1) of integrated luminosity collected by the D0 Collaboration at the Tevatron pp Collider. The ...total width Gammat is extracted from the partial decay width Gamma(t arrow right Wb) and the branching fraction B(t arrow right Wb). Gamma(t arrow right Wb) is obtained from the t-channel single top-quark production cross section and B(t arrow right Wb) is measured in tt events. For a top mass of 172.5 GeV, the resulting width is Gammat= (ProQuest: Formulae and/or non-USASCII text omitted) GeV. This translates to a top-quark lifetime of taut = (ProQuest: Formulae and/or non-USASCII text omitted) x 10 super(-25) s. We also extract an improved direct limit on the Cabibbo-Kobayashi-Maskawa quark-mixing matrix element 0.81 < Vtb < or = 1 at 95% C.L. and a limit of Vtb' < 0.59 for a high-mass fourth-generation bottom quark assuming unitarity of the fourth-generation quark-mixing matrix.
We present a measurement of the inclusive jet cross section using the Run II cone algorithm and data collected by the D0 experiment in p (p) over bar collisions at a center-of-mass energy root s = ...1.96 TeV, corresponding to an integrated luminosity of 0: 70 fb(-1). The jet energy calibration and the method used to extract the inclusive jet cross section are described. We discuss the main uncertainties, which are dominated by the jet energy scale uncertainty. The results cover jet transverse momenta from 50 GeV to 600 GeV with jet rapidities in the range -2.4 to 2.4 and are compared to predictions using recent proton parton distribution functions. Studies of correlations between systematic uncertainties in transverse momentum and rapidity are presented.
We report a search for a narrow t (t) over bar resonance that decays into a lepton + jets final state based on an integrated luminosity of 5.3 fb(-1) of proton-antiproton collisions at root s = 1.96 ...TeV collected by the D0 Collaboration at the Fermilab Tevatron Collider. We set upper limits on the production cross section of such a resonance multiplied by its branching fraction to t (t) over bar. We exclude a leptophobic topcolor Z' at the 95% confidence level for masses below 835 GeV (940 GeV) if its width is 1.2% (3%) of its mass. We also exclude color octet vector bosons (colorons) with masses below 775 GeV.
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