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V M Abazov,
B Abbott,
B S Acharya, M Adams,
T Adams,
G D Alexeev,
G Alkhazov,
A Alton,
G Alverson,
G A Alves, [......],
K Yip,
S W Youn,
J Yu,
S Zelitch,
T Zhao,
B Zhou,
J Zhu,
M Zielinski,
D Zieminska,
L Zivkovic
[show abstract]
[hide abstract]
ABSTRACT: We measure the top quark mass (m(t)) in p ̄p collisions at a center of mass energy √s = 1.96 TeV using dilepton t ̄t→W(+)bW(-) ̄b→ℓ(+)ν(ℓ)bℓ(-) ̄ν(ℓ) ̄b events, where ℓ denotes an electron, a muon, or a tau that decays leptonically. The data correspond to an integrated luminosity of 5.4 fb(-1) collected with the D0 detector at the Fermilab Tevatron Collider. We obtain m(t)=174.0±1.8(stat)±2.4(syst) GeV, which is in agreement with the current world average m(t)=173.3±1.1 GeV. This is currently the most precise measurement of m(t) in the dilepton channel.
Physical Review Letters 08/2011; 107(8):082004. · 7.37 Impact Factor
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V M Abazov,
B Abbott,
B S Acharya, M Adams,
T Adams,
G D Alexeev,
G Alkhazov,
A Alton,
G Alverson,
G A Alves, [......],
K Yip,
S W Youn,
J Yu,
S Zelitch,
T Zhao,
B Zhou,
J Zhu,
M Zielinski,
D Zieminska,
L Zivkovic
[show abstract]
[hide abstract]
ABSTRACT: We present a search for pair production of a fourth generation t' quark and its antiparticle, followed by their decays to a W boson and a jet, based on an integrated luminosity of 5.3 fb(-1) of proton-antiproton collisions at √s = 1.96 TeV collected by the D0 Collaboration at the Fermilab Tevatron Collider. We set upper limits on the t' ̄t' production cross section that exclude at the 95% C.L. a t' quark that decays exclusively to W+jet with a mass below 285 GeV. We observe a small excess in the μ+jets channel which reduces the mass range excluded compared to the expected limit of 320 GeV in the absence of a signal.
Physical Review Letters 08/2011; 107(8):082001. · 7.37 Impact Factor
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V M Abazov,
B Abbott,
B S Acharya, M Adams,
T Adams,
G D Alexeev,
G Alkhazov,
A Alton,
G Alverson,
G A Alves, [......],
K Yip,
S W Youn,
J Yu,
S Zelitch,
T Zhao,
B Zhou,
J Zhu,
M Zielinski,
D Zieminska,
L Zivkovic
[show abstract]
[hide abstract]
ABSTRACT: We determine the fraction of tt events with spin correlation, assuming that the spin of the top quark is either correlated with the spin of the top antiquark as predicted by the standard model or is uncorrelated. For the first time we use a matrix-element-based approach to study tt spin correlation. We use tt → W+ b W- b → ℓ+ νbℓ- ν b final states produced in pp collisions at a center-of-mass energy sqrt(s)=1.96 TeV, where ℓ denotes an electron or a muon. The data correspond to an integrated luminosity of 5.4 fb(-1) and were collected with the D0 detector at the Fermilab Tevatron collider. The result agrees with the standard model prediction. We exclude the hypothesis that the spins of the tt are uncorrelated at the 97.7% C.L.
Physical Review Letters 07/2011; 107(3):032001. · 7.37 Impact Factor
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V M Abazov,
B Abbott,
B S Acharya, M Adams,
T Adams,
G D Alexeev,
G Alkhazov,
A Alton,
G Alverson,
G A Alves, [......],
K Yip,
S W Youn,
J Yu,
S Zelitch,
T Zhao,
B Zhou,
J Zhu,
M Zielinski,
D Zieminska,
L Zivkovic
[show abstract]
[hide abstract]
ABSTRACT: We search for resonant WW or WZ production by using up to 5.4 fb(-1) of integrated luminosity collected by the D0 experiment in run II of the Fermilab Tevatron Collider. The data are consistent with the standard model background expectation, and we set limits on a resonance mass by using the sequential standard model W' boson and the Randall-Sundrum model graviton G as benchmarks. We exclude a sequential standard model W' boson in the mass range 180-690 GeV and a Randall-Sundrum graviton in the range 300-754 GeV at 95% C.L.
Physical Review Letters 07/2011; 107(1):011801. · 7.37 Impact Factor
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V M Abazov,
B Abbott,
B S Acharya, M Adams,
T Adams,
G D Alexeev,
G Alkhazov,
A Alton,
G Alverson,
G A Alves, [......],
K Yip,
S W Youn,
J Yu,
S Zelitch,
T Zhao,
B Zhou,
J Zhu,
M Zielinski,
D Zieminska,
L Zivkovic
[show abstract]
[hide abstract]
ABSTRACT: We present a study of the dijet invariant mass spectrum in events with two jets produced in association with a W boson in data corresponding to an integrated luminosity of 4.3 fb(-1) collected with the D0 detector at √s = 1.96 TeV. We find no evidence for anomalous resonant dijet production and derive upper limits on the production cross section of an anomalous dijet resonance recently reported by the CDF Collaboration, investigating the range of dijet invariant mass from 110 to 170 GeV/c(2). The probability of the D0 data being consistent with the presence of a dijet resonance with 4 pb production cross section at 145 GeV/c(2) is 8×10(-6).
Physical Review Letters 07/2011; 107(1):011804. · 7.37 Impact Factor
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V M Abazov,
B Abbott,
B S Acharya, M Adams,
T Adams,
G D Alexeev,
G Alkhazov,
A Alton,
G Alverson,
G A Alves, [......],
K Yip,
S W Youn,
J Yu,
S Zelitch,
T Zhao,
B Zhou,
J Zhu,
M Zielinski,
D Zieminska,
L Zivkovic
[show abstract]
[hide abstract]
ABSTRACT: We present a search for the standard model Higgs boson (H) in pp collisions at sqrt(s)=1.96 TeV in events containing a charged lepton (ℓ), missing transverse energy, and at least two jets, using 5.4 fb(-1) of integrated luminosity recorded with the D0 detector at the Fermilab Tevatron Collider. This analysis is sensitive primarily to Higgs bosons produced through the fusion of two gluons or two electroweak bosons, with subsequent decay H→WW→ℓνq'q, where ℓ is an electron or muon. The search is also sensitive to contributions from other production channels, such as WH→ℓνbb. In the absence of a signal, we set limits at the 95% C.L. on the cross section for H production σ(pp→H+X) in these final states. For a mass of M(H)=160 GeV, the limit is a factor of 3.9 larger than the cross section in the standard model and consistent with an a priori expected sensitivity of 5.0.
Physical Review Letters 04/2011; 106(17):171802. · 7.37 Impact Factor
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V M Abazov,
B Abbott,
M Abolins,
B S Acharya, M Adams,
T Adams,
G D Alexeev,
G Alkhazov,
A Alton,
G Alverson, [......],
H D Yoo,
S W Youn,
J Yu,
S Zelitch,
T Zhao,
B Zhou,
J Zhu,
M Zielinski,
D Zieminska,
L Zivkovic
[show abstract]
[hide abstract]
ABSTRACT: Using 7.3 fb⁻¹ of pp collisions collected by the D0 detector at the Fermilab Tevatron, we measure the distribution of the variable φ(η)*, which probes the same physical effects as the Z/γ* boson transverse momentum, but is less susceptible to the effects of experimental resolution and efficiency. A QCD prediction is found to describe the general features of the φ(η)* distribution, but is unable to describe its detailed shape or dependence on boson rapidity. A prediction that includes a broadening of transverse momentum for small values of the parton momentum fraction is strongly disfavored.
Physical Review Letters 03/2011; 106(12):122001. · 7.37 Impact Factor
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V M Abazov,
B Abbott,
B S Acharya, M Adams,
T Adams,
G D Alexeev,
G Alkhazov,
A Alton,
G Alverson,
G A Alves, [......],
K Yip,
S W Youn,
J Yu,
S Zelitch,
T Zhao,
B Zhou,
J Zhu,
M Zielinski,
D Zieminska,
L Zivkovic
[show abstract]
[hide abstract]
ABSTRACT: We present a search for hypothetical vectorlike quarks in pp ̅ collisions at √s=1.96 TeV. The data were collected by the D0 detector at the Fermilab Tevatron Collider and correspond to an integrated luminosity of 5.4 fb(-1). We select events with a final state composed of a W or Z boson and a jet consistent with a heavy object decay. We observe no significant excess in comparison to the background prediction and set limits on production cross sections for vectorlike quarks decaying to W+jet and Z+jet. These are the most stringent limits to date for electroweak single vectorlike quark production at hadron colliders.
Physical Review Letters 02/2011; 106(8):081801. · 7.37 Impact Factor
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V M Abazov,
B Abbott,
M Abolins,
B S Acharya, M Adams,
T Adams,
G D Alexeev,
G Alkhazov,
A Alton,
G Alverson, [......],
H D Yoo,
S W Youn,
J Yu,
S Zelitch,
T Zhao,
B Zhou,
J Zhu,
M Zielinski,
D Zieminska,
L Zivkovic
[show abstract]
[hide abstract]
ABSTRACT: We extract the total width of the top quark, Γ(t), from the partial decay width Γ(t → Wb) measured using the t-channel cross section for single top-quark production and from the branching fraction B(t → Wb) measured in tt events using up to 2.3 fb(-1) of integrated luminosity collected by the D0 Collaboration at the Tevatron pp Collider. The result is Γ(t) = 1.99(-0.55)(+0.69) GeV, which translates to a top-quark lifetime of τ(t) = (3.3(-0.9)(+1.3)) × 10(-25) s. Assuming a high mass fourth generation b' quark and unitarity of the four-generation quark-mixing matrix, we set the first upper limit on |V(tb')| < 0.63 at 95% C.L.
Physical Review Letters 01/2011; 106(2):022001. · 7.37 Impact Factor
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V M Abazov,
B Abbott,
M Abolins,
B S Acharya, M Adams,
T Adams,
G D Alexeev,
G Alkhazov,
A Alton,
G Alverson, [......],
H D Yoo,
S W Youn,
J Yu,
S Zelitch,
T Zhao,
B Zhou,
J Zhu,
M Zielinski,
D Zieminska,
L Zivkovic
[show abstract]
[hide abstract]
ABSTRACT: We present a search for the standard model Higgs boson produced in association with a Z boson in 4.2 fb(-1) of pp collisions, collected with the D0 detector at the Fermilab Tevatron at sqrt[s] =1 .96 TeV. Selected events contain one reconstructed Z → e+ e- or Z → μ+ μ- candidate and at least two jets, including at least one b-tagged jet. In the absence of an excess over the background expected from other standard model processes, limits on the ZH cross section multiplied by the branching ratios are set. The limit at M(H) = 115 GeV is a factor of 5.9 larger than the standard model prediction.
Physical Review Letters 12/2010; 105(25):251801. · 7.37 Impact Factor
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V M Abazov,
B Abbott,
M Abolins,
B S Acharya, M Adams,
T Adams,
G D Alexeev,
G Alkhazov,
A Alton,
G Alverson, [......],
S W Youn,
J Yu,
S Zelitch,
T Zhao,
B Zhou,
N Zhou,
J Zhu,
M Zielinski,
D Zieminska,
L Zivkovic
[show abstract]
[hide abstract]
ABSTRACT: We report a search for diphoton events with large missing transverse energy produced in pp collisions at √s=1.96 TeV. The data were collected with the D0 detector at the Fermilab Tevatron Collider and correspond to 6.3 fb(-1) of integrated luminosity. The observed missing transverse energy distribution is well described by the standard model prediction, and 95% C.L. limits are derived on two realizations of theories beyond the standard model. In a gauge-mediated supersymmetry breaking scenario, the breaking scale Λ is excluded for Λ<124 TeV. In a universal extra dimension model including gravitational decays, the compactification radius R(c) is excluded for R(c)(-1)<477 GeV.
Physical Review Letters 11/2010; 105(22):221802. · 7.37 Impact Factor
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V M Abazov,
B Abbott,
M Abolins,
B S Acharya, M Adams,
T Adams,
G D Alexeev,
G Alkhazov,
A Alton,
G Alverson, [......],
H D Yoo,
S W Youn,
J Yu,
S Zelitch,
T Zhao,
B Zhou,
J Zhu,
M Zielinski,
D Zieminska,
L Zivkovic
[show abstract]
[hide abstract]
ABSTRACT: We report the results of a search for R parity violating (RPV) interactions leading to the production of supersymmetric sneutrinos decaying into eμ final states using 5.3 fb-1 of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron Collider. Having observed no evidence for production of eμ resonances, we set direct bounds on the RPV couplings λ311' and λ312 as a function of sneutrino mass.
Physical Review Letters 11/2010; 105(19):191802. · 7.37 Impact Factor
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V M Abazov,
B Abbott,
M Abolins,
B S Acharya, M Adams,
T Adams,
G D Alexeev,
G Alkhazov,
A Alton,
G Alverson, [......],
H D Yoo,
S W Youn,
J Yu,
S Zelitch,
T Zhao,
B Zhou,
J Zhu,
M Zielinski,
D Zieminska,
L Zivkovic
[show abstract]
[hide abstract]
ABSTRACT: We present the first search for pair production of isolated jets of charged leptons in association with a large imbalance in transverse energy in pp collisions using 5.8 fb⁻¹ of integrated luminosity collected by the D0 detector at the Fermilab Tevatron Collider. No excess is observed above the standard model background, and the result is used to set upper limits on the production cross section of pairs of supersymmetric chargino and neutralino particles as a function of "dark-photon" mass, where the dark photon is produced in the decay of the lightest supersymmetric particle.
Physical Review Letters 11/2010; 105(21):211802. · 7.37 Impact Factor
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V M Abazov,
B Abbott,
M Abolins,
B S Acharya, M Adams,
T Adams,
G D Alexeev,
G Alkhazov,
A Alton,
G Alverson, [......],
H D Yoo,
S W Youn,
J Yu,
S Zelitch,
T Zhao,
B Zhou,
J Zhu,
M Zielinski,
D Zieminska,
L Zivkovic
[show abstract]
[hide abstract]
ABSTRACT: We report results of a search for particles with anomalously high ionization in events with a high transverse energy jet and large missing transverse energy in 2.4 fb⁻¹ of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron pp collider. Production of such particles (quirks) is expected in scenarios with extra QCD-like SU(N) sectors, and this study is the first dedicated search for such signatures. We find no evidence of a signal and set a lower mass limit of 107, 119, and 133 GeV for the mass of a charged quirk with strong dynamics scale Λ in the range from 10 keV to 1 MeV and N=2, 3, and 5, respectively.
Physical Review Letters 11/2010; 105(21):211803. · 7.37 Impact Factor
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V M Abazov,
B Abbott,
M Abolins,
B S Acharya, M Adams,
T Adams,
E Aguilo,
M Ahsan,
G D Alexeev,
G Alkhazov, [......],
C Zeitnitz,
S Zelitch,
T Zhao,
B Zhou,
J Zhu,
M Zielinski,
D Zieminska,
L Zivkovic,
V Zutshi,
E G Zverev
[show abstract]
[hide abstract]
ABSTRACT: We present the first search for an electrically charged resonance W' decaying to a WZ boson pair using 4.1 fb(-1) of integrated luminosity collected with the D0 detector at the Fermilab Tevatron pp collider. The WZ pairs are reconstructed through their decays into three charged leptons (l=e, mu). A total of 9 data events is observed in good agreement with the background prediction. We set 95% C.L. limits on the W'WZ coupling and on the W' production cross section multiplied by the branching fractions. We also exclude W' masses between 188 and 520 GeV within a simple extension of the standard model and set the most restrictive limits to date on low-scale technicolor models.
Physical Review Letters 02/2010; 104(6):061801. · 7.37 Impact Factor
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V M Abazov,
B Abbott,
M Abolins,
B S Acharya, M Adams,
T Adams,
E Aguilo,
G D Alexeev,
G Alkhazov,
A Alton, [......],
C Zeitnitz,
S Zelitch,
T Zhao,
B Zhou,
J Zhu,
M Zielinski,
D Zieminska,
L Zivkovic,
V Zutshi,
E G Zverev
[show abstract]
[hide abstract]
ABSTRACT: A search for the standard model Higgs boson is presented using events with two charged leptons and large missing transverse energy selected from 5.4 fb(-1) of integrated luminosity in pp collisions at square root(s) = 1.96 TeV collected with the D0 detector at the Fermilab Tevatron collider. No significant excess of events above background predictions is found, and observed (expected) upper limits at 95% confidence level on the rate of Higgs boson production are derived that are a factor of 1.55 (1.36) above the predicted standard model cross section at m(H) = 165 GeV.
Physical Review Letters 02/2010; 104(6):061804. · 7.37 Impact Factor
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V M Abazov,
B Abbott,
M Abolins,
B S Acharya, M Adams,
T Adams,
E Aguilo,
G D Alexeev,
G Alkhazov,
A Alton, [......],
C Zeitnitz,
S Zelitch,
T Zhao,
B Zhou,
J Zhu,
M Zielinski,
D Zieminska,
L Zivkovic,
V Zutshi,
E G Zverev
[show abstract]
[hide abstract]
ABSTRACT: A search is performed for the standard model Higgs boson in 5.2 fb{-1} of pp collisions at sqrt[s]=1.96 TeV, collected with the D0 detector at the Fermilab Tevatron Collider. The final state considered is a pair of b jets and large missing transverse energy, as expected from pp-->ZH-->nunubb production. The search is also sensitive to the WH-->lnubb channel when the charged lepton is not identified. For a Higgs boson mass of 115 GeV, a limit is set at the 95% C.L. on the cross section multiplied by branching fraction for [pp-->(Z/W)H](H-->bb) that is a factor of 3.7 larger than the standard model value, consistent with the factor of 4.6 expected.
Physical Review Letters 02/2010; 104(7):071801. · 7.37 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: This paper investigates an approach to quantify the problem of cross correlation between the prediction and observation noise of an inertial navigation system (INS), which utilizes a linear Kalman filter (KF). Cross correlation is shown being introduced by use of the transformation matrix to transform body frame velocity observations into navigation frame. The effect of the cross-correlation term on the error covariance matrix and subsequently on the convergence of the filter is evaluated theoretically. With the cross-correlation term being formulated from the prediction and observation noise, it is incorporated into the KF and thus the relevant filter equations have been updated accordingly. A simulation is produced to evaluate the effect of the cross-correlation term. The theoretical formulation and numerical simulations present the importance of incorporating this term into the filter and navigation system. If this term was ignored, the error covariance estimates associated with the positional estimates would be too small and the filter would be ¿over confident¿.
Technologies for Practical Robot Applications, 2009. TePRA 2009. IEEE International Conference on; 12/2009
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V M Abazov,
B Abbott,
M Abolins,
B S Acharya, M Adams,
T Adams,
E Aguilo,
M Ahsan,
G D Alexeev,
G Alkhazov, [......],
C Zeitnitz,
S Zelitch,
T Zhao,
B Zhou,
J Zhu,
M Zielinski,
D Zieminska,
L Zivkovic,
V Zutshi,
E G Zverev
[show abstract]
[hide abstract]
ABSTRACT: We present a direct measurement of the width of the W boson using the shape of the transverse mass distribution of W --> enu candidate events. Data from approximately 1 fb(-1) of integrated luminosity recorded at square root of s = 1.96 TeV by the D0 detector at the Fermilab Tevatron pp collider are analyzed. We use the same methods and data sample that were used for our recently published W boson mass measurement, except for the modeling of the recoil, which is done with a new method based on a recoil library. Our result, 2.028 +/- 0.072 GeV, is in agreement with the predictions of the standard model.
Physical Review Letters 12/2009; 103(23):231802. · 7.37 Impact Factor
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V M Abazov,
B Abbott,
M Abolins,
B S Acharya, M Adams,
T Adams,
E Aguilo,
M Ahsan,
G D Alexeev,
G Alkhazov, [......],
C Zeitnitz,
S Zelitch,
T Zhao,
B Zhou,
J Zhu,
M Zielinski,
D Zieminska,
L Zivkovic,
V Zutshi,
E G Zverev
[show abstract]
[hide abstract]
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-->lnul'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.
Physical Review Letters 11/2009; 103(19):191801. · 7.37 Impact Factor
