1. |
- Aaltonen, T., et al.
(författare)
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Combination of Tevatron Searches for the Standard Model Higgs Boson in the W+W- Decay Mode
- 2010
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 104:6, s. 061802-
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Tidskriftsartikel (refereegranskat)abstract
- We combine searches by the CDF and D0 Collaborations for a Higgs boson decaying to W+W-. The data correspond to an integrated total luminosity of 4.8 (CDF) and 5.4 (D0) fb(-1) of p (p) over bar collisions at root s = 1.96 TeV at the Fermilab Tevatron collider. No excess is observed above background expectation, and resulting limits on Higgs boson production exclude a standard model Higgs boson in the mass range 162-166 GeV at the 95% C.L.
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2. |
- Abazov, V. M., et al.
(författare)
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Search for CP violation in B-s(0) -> mu(+) D-s(-) X decays in p(p)over-bar collisions at root s=1.96 TeV
- 2010
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Ingår i: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 1550-7998 .- 1550-2368. ; 82:1, s. 012003-
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Tidskriftsartikel (refereegranskat)abstract
- We have performed a search for CP violation in a sample of B-s(0) -> mu+Ds-X decays corresponding to 5 fb(-1) of proton-antiproton collisions collected by the D0 detector in Run II at the Fermilab Tevatron Collider. New physics in B-s(0) mixing could contribute a significant CP violating weak phase, which would be observed as a difference in the decay-time distribution for B-s(0) -> (B) over bar (0)(s) oscillated states versus that for (B) over bar (0)(s) -> B-s(0). A fit to the decay-time distributions of the B-s(0)/(B) over bar (0)(s) candidates yields the flavor-specific asymmetry as a(fs)(s) = [-1.7 +/- 9.1(stat)(-1.5)(+1.4)(syst) x 10(-3), which excludes CP violation due to new physics within the experimental sensitivity.
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3. |
- Abazov, V. M., et al.
(författare)
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Measurement of the t-channel single top quark production cross section
- 2010
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 682:4-5, s. 363-369
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Tidskriftsartikel (refereegranskat)abstract
- The DO Collaboration reports direct evidence for electroweak production of single top quarks through the t-channel exchange of a virtual W boson. This is the first analysis to isolate an individual single top quark production channel. We select events containing an isolated electron or muon, missing transverse energy, and two, three or four jets from 2.3 fb(-1) of p (p) over bar collisions at the Fermilab Tevatron Collider. One or two of the jets are identified as containing a b hadron. We combine three multivariate techniques optimized for the t-channel process to measure the t- and s-channel cross sections simultaneously. We measure cross sections of 3.14(-0.80)(+0.94) pb for the t-channel and 1.05 +/- 0.81 pb for the s-channel. The measured t-channel result is found to have a significance of 4.8 standard deviations and is consistent with the standard model prediction.
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4. |
- Abazov, V. M., et al.
(författare)
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Measurement of Z/gamma* plus jet plus X angular distributions in p(p)over-bar collisions at root s=1.96 TeV
- 2010
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 682:4-5, s. 370-380
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Tidskriftsartikel (refereegranskat)abstract
- We present the first measurements at a hadron collider of differential cross sections for Z/gamma* + jet + X production in Delta phi(Z. jet), vertical bar Delta y(Z, jet)vertical bar and vertical bar y(boost)(Z + jet)vertical bar. Vector boson production in association with jets is an excellent probe of QCD and constitutes the main background to many small cross section processes, such as associated Higgs production. These measurements are crucial tests of the predictions of perturbative QCD and current event generators, which have varied success in describing the data. Using these measurements as inputs in tuning event generators will increase the experimental sensitivity to rare signals.
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5. |
- Abazov, V. M., et al.
(författare)
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Search for single top quarks in the tau plus jets channel using 4.8 fb(-1) of p(p)over-bar collision data
- 2010
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 690:1, s. 5-14
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Tidskriftsartikel (refereegranskat)abstract
- We present the first direct search for single top quark production using reconstructed tau leptons in the final state. The search is based on 4.8 fb(-1) of integrated luminosity collected in p (p) over bar collisions at root s= 1.96 TeV with the D0 detector at the Fermilab Tevatron Collider. We select events with a final state including an isolated tau lepton. missing transverse energy, two or three jets, one or two of them being identified as b quark jet. We use a multivariate technique to discriminate signal from background. The number of events observed in data in this final state is consistent with the signal plus background expectation. We set in the tau + jets channel an upper limit on the single top quark cross section of 7.3 pb at the 95% C.L. This measurement allows a gain of 4% in expected sensitivity for the observation of single top production when combining it with electron + jets and muon + jets channels already published by the DO Collaboration with 2.3 fb(-1) of data. We measure a combined cross section of 3.84(-0.83)(+0.89) pb, which is the most precise measurement to date.
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6. |
- Abazov, V. M., et al.
(författare)
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Search for the Standard Model Higgs Boson in the ZH -> v(v)over-barb(b)over-bar Channel in 5.2 fb(-1) of p(p)over-bar Collisions at root s=1.96 TeV
- 2010
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 104:7, s. 071801-
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Tidskriftsartikel (refereegranskat)abstract
- A search is performed for the standard model Higgs boson in 5.2 fb(-1) of p (p) over bar collisions at root 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 p (p) over bar -> ZH -> v (v) over barb (b) over bar production. The search is also sensitive to the WH -> lvb (b) over bar 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 [p (p) over bar -> (Z/W)H](H -> b (b) over bar) that is a factor of 3.7 larger than the standard model value, consistent with the factor of 4.6 expected.
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7. |
- Abazov, V. M., et al.
(författare)
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Double parton interactions in gamma+3 jet events in p(p)over-bar collisions at root s=1.96 TeV
- 2010
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 81:5, s. 052012-
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Tidskriftsartikel (refereegranskat)abstract
- We have used a sample of gamma + 3 jets events collected by the D0 experiment with an integrated luminosity of about 1 fb(-1) to determine the fraction of events with double parton scattering (f(DP)) in a single p (p) over bar collision at root s = 1.96 TeV. The DP fraction and effective cross section (sigma(eff)), a process-independent scale parameter related to the parton density inside the nucleon, are measured in three intervals of the second (ordered in p(T)) jet transverse momentum p(T)(jet2) within the range 15 <= p(T)(jet2) <= 30 GeV. In this range, f(DP) varies between 0.23 <= f(DP) <= 0.47, while sigma(eff) has the average value sigma(ave)(eff) = 16.4 +/- 0.3(stat) +/- 2.3(syst) mb.
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8. |
- Abazov, V. M., et al.
(författare)
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Measurement of the t(t)over-bar cross section using high-multiplicity jet events
- 2010
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 82, s. 032002-
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Tidskriftsartikel (refereegranskat)abstract
- We present a measurement of the t (t) over bar cross section using high-multiplicity jet events produced in p (p) over bar collisions at root s = 1.96 TeV. These data were recorded at the Fermilab Tevatron Collider with the D0 detector. Events with at least six jets, two of them identified as b jets, were selected from a 1 fb(-1) data set. The measured cross section, assuming a top quark mass of 175 GeV/c(2), is 6.9 +/- 2.0 pb, in agreement with theoretical expectations.
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9. |
- Abazov, V. M., et al.
(författare)
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Search for a Resonance Decaying into WZ Boson Pairs in p(p)over-bar Collisions
- 2010
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 104:6, s. 061801-
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Tidskriftsartikel (refereegranskat)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 p (p) over bar 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.
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10. |
- Abazov, V. M., et al.
(författare)
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Search for Higgs Boson Production in Dilepton and Missing Energy Final States with 5.4 fb(-1) of p(p)over-bar Collisions at root s=1.96 TeV
- 2010
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 104:6, s. 061804-
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Tidskriftsartikel (refereegranskat)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 p ($) over bar collisions at 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.
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