1. |
- Abazov, M, et al.
(author)
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Combination of t(t)over-bar cross section measurements and constraints on the mass of the top quark and its decays into charged Higgs bosons
- 2009
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In: Physical Review D. - 1550-7998 .- 1550-2368. ; 80, s. 071102-
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Journal article (peer-reviewed)abstract
- We combine measurements of the top quark pair production cross section in p (p) over bar collisions in the l + jets, ll, and tau l final states ( where l is an electron or muon) at a center of mass energy of root s = 1.96 TeV in 1 fb(-1) of data collected with the D0 detector. For a top quark mass of 170 GeV/c(2), we obtain sigma(t (t) over bar) = 8.18(-0.87)(+0.98) pb in agreement with the theoretical prediction. Based on predictions from higher order quantum chromodynamics, we extract a mass for the top quark from the combined t (t) over bar cross section, consistent with the world average of the top quark mass. In addition, the ratios of t (t) over bar cross sections in different final states are used to set upper limits on the branching fractions B(t -> H(+)b -> tau(+) vb) and B(t -> H(+)b -> c (s) over barb) as a function of the charged Higgs boson mass.
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2. |
- Abazov, M, et al.
(author)
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Direct Measurement of the Mass Difference between Top and Antitop Quarks
- 2009
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 103:13, s. 132001-
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Journal article (peer-reviewed)abstract
- We present a measurement of the mass difference between t and (t) over bar quarks in lepton + jets final states of t (t) over bar events in 1 fb(-1) of data collected with the D0 detector from Fermilab Tevatron Collider p (p) over bar collisions at root s = 1.96 TeV. The measured mass difference of 3.8 +/- 3.7 GeV is consistent with the equality of t and (t) over bar masses. This is the first direct measurement of a mass difference between a quark and its antiquark partner.
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3. |
- Abazov, M, et al.
(author)
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Evidence of WW and WZ Production with lepton plus jets Final States in pp Collisions at root s=1.96 TeV
- 2009
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:16, s. 161801-
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Journal article (peer-reviewed)abstract
- We present first evidence for WW+WZ production in lepton+jets final states at a hadron collider. The data correspond to 1.07 fb(-1) of integrated luminosity collected with the D0 detector at the Fermilab Tevatron in pp collisions at root s=1.96 TeV. The observed cross section for WW+WZ production is 20.2 +/- 4.5 pb, consistent with the standard model and more precise than previous measurements in fully leptonic final states. The probability that background fluctuations alone produce this excess is < 5.4x10(-6), which corresponds to a significance of 4.4 standard deviations.
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4. |
- Abazov, M, et al.
(author)
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Measurement of B-s(0) Mixing Parameters from the Flavor-Tagged Decay B-s(0)-> J/psi phi
- 2008
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 101:24, s. 241801-:101, s. 241801-
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Journal article (peer-reviewed)abstract
- From an analysis of the flavor-tagged decay B-s(0)-> J/psi phi we obtain the width difference between the B-s(0) light and heavy mass eigenstates, Delta Gamma(s)=0.19 +/- 0.07(stat)(-0.01)(+0.02)(syst) ps(-1), and the CP-violating phase, phi(s)=-0.57(-0.30)(+0.24)(stat)(-0.02)(+0.08)(syst). The allowed 90% CL intervals of Delta Gamma(s) and phi(s) are 0.06
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5. |
- Abazov, M, et al.
(author)
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Measurement of differential Z/gamma* plus jet plus X cross sections in p(p)over-bar collisions at root S=1.96 TeV
- 2008
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In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 669:5, s. 278-286
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Journal article (peer-reviewed)abstract
- We present new measurements of differential cross sections for Z/gamma* (-> mu mu) + jet + X production in a 1 fb(-1) data sample collected with the DO detector in p (p) over bar collisions at root s = 1.96 TeV. Results include the first measurements differential in the Z/gamma* transverse momentum and rapidity, as well as new measurements differential in the leading jet transverse momentum and rapidity. Next-to-leading order perturbative QCD predictions are compared to the measurements, and reasonable agreement is observed, except in the region of low Z/gamma* transverse momentum. Predictions from two event generators based on matrix elements and parton showers, and one pure parton shower event generator are also compared to the measurements. These show significant overall normalization differences to the data and have varied success in describing the shape of the distributions.
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6. |
- Abazov, M, et al.
(author)
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Measurement of Dijet Angular Distributions at s=1.96 TeV and Searches for Quark Compositeness and Extra Spatial Dimensions
- 2009
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 103:19, s. 191803-
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Journal article (peer-reviewed)abstract
- We present the first measurement of dijet angular distributions in pp collisions at s=1.96 TeV at the Fermilab Tevatron Collider. The measurement is based on a dataset corresponding to an integrated luminosity of 0.7 fb(-1) collected with the D0 detector. Dijet angular distributions have been measured over a range of dijet masses, from 0.25 TeV to above 1.1 TeV. The data are in good agreement with the predictions of perturbative QCD and are used to constrain new physics models including quark compositeness, large extra dimensions, and TeV-1 scale extra dimensions. For all models considered, we set the most stringent direct limits to date.
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7. |
- Abazov, M, et al.
(author)
-
Measurement of gamma + b + X and gamma + c + X Production Cross Sections in pp > Collisions at s=1.96 TeV
- 2009
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:19, s. 192002-
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Journal article (peer-reviewed)abstract
- First measurements of the differential cross sections d(3)sigma/(dp(T)(gamma)dy(gamma)dy(jet)) for the inclusive production of a photon in association with a heavy quark (b, c) jet are presented, covering photon transverse momenta 30 < p(T)(gamma)< 150 GeV, photon rapidities |y(gamma)|< 1.0, jet rapidities |y(jet)|< 0.8, and jet transverse momenta p(T)(jet)> 15 GeV. The results are based on an integrated luminosity of 1 fb(-1) in pp collisions at s=1.96 TeV recorded with the D0 detector at the Fermilab Tevatron Collider. The results are compared with next-to-leading order perturbative QCD predictions.
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8. |
- Abazov, M, et al.
(author)
-
Measurement of the t(t)over-bar production cross section and top quark mass extraction using dilepton events in p(p)over-bar collisions
- 2009
-
In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 679:3, s. 177-185
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Journal article (peer-reviewed)abstract
- We present a measurement of the top quark pair production cross section in p (p) over bar collisions at root s = 1.96 TeV using approximately 1 fb(-1) collected with the DO detector. We consider decay channels containing two high p(T) charged leptons where one lepton is identified as an electron or a muon while the other lepton can be an electron, a muon or a hadronically decaying tau lepton. For a mass of the top quark of 170 GeV, the measured cross section is 7.5(-1.0)(+1.0)(stat)(-0.6)(+0.7)(syst)(-0.5)(+0.6)(lumi) pb. Using l tau events only, we measure: sigma(t (t) over bar) x B(t (t) over bar -> l tau b (b) over bar) = 0.13(-0.08)(+0.09)(stat)(-0.06)(+0.06)(syst)(-0.02)(+0.02)(lumi) pb. Comparing the measured cross section as a function of the mass of the top quark with a partial next-to-next-to leading order Quantum Chroniodynamics theoretical prediction, we extract a mass of the top quark of 171.5(-8.8)(+9-9) GeV, in agreement with direct measurements.
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9. |
- Abazov, M, et al.
(author)
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Measurement of the WW Production Cross Section with Dilepton Final States in pp Collisions at s=1.96 TeV and Limits on Anomalous Trilinear Gauge Couplings
- 2009
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 103:19, s. 191801-
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Journal article (peer-reviewed)abstract
- We provide the most precise measurement of the WW production cross section in pp collisions to date at a center of mass energy of 1.96 TeV, and set limits on the associated trilinear gauge couplings. The WW -> l nu l(')nu (l, l(')=e, mu) decay channels are analyzed in 1 fb(-1) of data collected by the D0 detector at the Fermilab Tevatron Collider. The measured cross section is sigma(pp -> WW)=11.5 +/- 2.1(stat+syst)+/- 0.7(lumi) pb. One- and two-dimensional 95% C.L. limits on trilinear gauge couplings are provided.
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10. |
- Abazov, M, et al.
(author)
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Measurement of the Z gamma -> nu(nu)over-bar gamma Production Cross Section and Limits on Anomalous ZZ gamma and Z gamma gamma Couplings in p(p)over-bar Collisions at root s=1.96 TeV
- 2009
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:20, s. 201802-
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Journal article (peer-reviewed)abstract
- We present the first observation of the Z gamma -> nu(nu) over bar gamma process at the Fermilab Tevatron at 5.1 standard deviations significance, based on 3.6 fb(-1) of integrated luminosity collected with the D0 detector at the Fermilab Tevatron p (p) over bar Collider at root s = 1.96 TeV. The measured Z gamma production cross section multiplied by the branching fraction of Z -> nu(nu) over bar is 32 +/- 9(stat + syst) +/- 2(lumi) fb for the photon E-T > 90 GeV. It is in agreement with the standard model prediction of 39 +/- 4 fb. We set limits on anomalous trilinear Z gamma gamma and ZZ gamma gauge boson couplings, most of which are the most restrictive to date.
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