61. |
- Abazov, V. M., et al.
(författare)
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Precise measurement of the top-quark mass from lepton plus jets events at D0
- 2011
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 84:3, s. 032004-
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Tidskriftsartikel (refereegranskat)abstract
- We report a measurement of the mass of the top quark in lepton + jets final states of p (p) over bar -> t (t) over bar data corresponding to 2.6 fb(-1) of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron Collider. A matrix-element method is developed that combines an in situ jet energy calibration with our standard jet energy scale derived from studies of gamma + jet and dijet events. We then implement a flavor-dependent jet-response correction through a novel approach. This method is used to measure a top-quark mass of m(t) = 176.01 +/- 1.64 GeV. Combining this result with our previous result obtained on an independent data set, we measure a top-quark mass of m(t) = 174.94 +/- 1.49 GeV for a total integrated luminosity of 3.6 fb(-1).
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62. |
- Abazov, V. M., et al.
(författare)
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Precise Measurement of the Top Quark Mass in the Dilepton Channel at D0
- 2011
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 107:8, s. 082004-
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Tidskriftsartikel (refereegranskat)abstract
- We measure the top quark mass (m(t)) in p (p) over bar collisions at a center of mass energy root s = 1.96 TeV using dilepton t (t) over bar -> W(+)bW(-)b(-) -> l(+)nu(l)bl(-)(nu) over bar (l)(b) over bar 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 mt in the dilepton channel.
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63. |
- Abazov, V. M., et al.
(författare)
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Precision Measurement of the Ratio B(t -> Wb)/B(t -> Wq) and Extraction of V(tb)
- 2011
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 107:12, s. 121802-
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Tidskriftsartikel (refereegranskat)abstract
- We present a measurement of the ratio of top quark branching fractions R = B(t -> Wb)/B(t -> Wq), where q can be a d, s, or b quark, in the lepton + jets and dilepton t (t) over bar final states. The measurement uses data from 5: 4 fb(-1) of p (p) over bar collisions collected with the D0 detector at the Fermilab Tevatron Collider. We measure R = 0.90 +/- 0.04, and we extract the Cabibbo-Kobayashi-Maskawa (CKM) matrix element vertical bar V(tb)vertical bar as vertical bar V(tb)vertical bar = 0.95 +/- 0.02, assuming unitarity of the 3 x 3 CKM matrix.
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64. |
- Abazov, V. M., et al.
(författare)
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Search for a Fermiophobic and Standard Model Higgs Boson in Diphoton Final States
- 2011
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 107:15, s. 151801-
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Tidskriftsartikel (refereegranskat)abstract
- We present a search for the standard model Higgs boson and a fermiophobic Higgs boson in the diphoton final states based on 8.2 fb(-1) of p (p) over bar collisions at root s = 1.96 TeV collected with the D0 detector at the Fermilab Tevatron Collider. No excess of data above background predictions is observed and upper limits at the 95% C.L. on the cross section multiplied by the branching fraction are set which are the most restrictive to date. A fermiophobic Higgs boson with a mass below 112.9 GeV is excluded at the 95% C.L.
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65. |
- Abazov, V. M., et al.
(författare)
-
Search for a Fourth Generation t ' Quark in p(p)over-bar Collisions at root s=1.96 TeV
- 2011
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 107:8, s. 082001-
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Tidskriftsartikel (refereegranskat)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 root s = 1.96 TeV collected by the D0 Collaboration at the Fermilab Tevatron Collider. We set upper limits on the t'(t) over bar' 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 mu + jets channel which reduces the mass range excluded compared to the expected limit of 320 GeV in the absence of a signal.
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66. |
- Abazov, V. M., et al.
(författare)
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Search for associated Higgs boson production using like charge dilepton events in p(p)over-bar collisions at root s=1.96 TeV
- 2011
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 84, s. 092002-
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Tidskriftsartikel (refereegranskat)abstract
- We present a search for associated Higgs boson production in the process p (p) over bar -> W/ZH -> l(+/-)l'(+/-) + X in ee, e mu, and mu mu final states. The search is based on data collected by the D0 experiment at the Fermilab Tevatron Collider at root s = 1.96 TeV corresponding to 5.3 fb(-1) of integrated luminosity. We require two isolated leptons (electrons or muons) with the same electric charge and additional kinematic requirements. No significant excess above background is observed, and we set 95% C. L. observed (expected) upper limits on ratio of the production cross section to the standard model prediction of 6.4 (7.3) for a Higgs boson mass of 165 GeV and 13.5 (19.8) for a mass of 115 GeV.
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67. |
- Abazov, V. M., et al.
(författare)
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Search for Doubly Charged Higgs Boson Pair Production in p(p)over-bar Collisions at root s=1.96 TeV
- 2012
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 108:2, s. 021801-
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Tidskriftsartikel (refereegranskat)abstract
- We present a search for pair production of doubly charged Higgs bosons in the processes q (q) over bar -> H(++)H(--) decaying through H(+/-+/-) ->tau(+/-)tau(+/-), mu(+/-)tau(+/-), mu(+/-)mu(+/-). The search is performed in p (p) over bar collisions at a center-of-mass energy of root s = 1:96 TeV using an integrated luminosity of up to 7:0 fb(-1) collected by the D0 experiment at the Fermilab Tevatron Collider. The results are used to set 95% C. L. limits on the pair production cross section of doubly charged Higgs bosons and on their mass for different H(+/-+/-) branching fractions. Models predicting different H(+/-+/-) decays are investigated. Assuming B(H(+/-+/-) -> tau(+/-)tau(+/-)) = 1 yields an observed (expected) lower limit on the mass of a left- handed H(L)(+/-+/-) boson of 128 (116) GeV and assuming B(H(+/-+/-) -> mu(+/-)tau(+/-)) = 1 the corresponding limits are 144 (149) GeV. In a model with B(H(+/-+/-) -> tau +/-tau(+/-) B(H(+/-+/-) -> mu(+/-)tau(+/-)) = B(H(+/-+/-) -> mu(+/-)mu(+/-) ) 1/3, we obtain M(H(L)(+/-+/-)) > 130 (138) GeV.
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68. |
- Abazov, V. M., et al.
(författare)
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Search for first generation leptoquark pair production in the electron plus missing energy plus jets final state
- 2011
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 84:7, s. 071104-
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Tidskriftsartikel (refereegranskat)abstract
- We present a search for the pair production of first generation scalar leptoquarks (LQ) in data corresponding to an integrated luminosity of 5.4 fb(-1) collected with the D0 detector at the Fermilab Tevatron Collider in p (p) over bar collisions at root s = 1.96 TeV. In the channel LQLQ -> eqv(e)q', where q, q' are u or d quarks, no significant excess of data over background is observed, and we set a 95% C. L. lower limit of 326 GeV on the LQ mass, assuming equal probabilities of LQ decays to eq and v(e)q'.
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69. |
- Abazov, V. M., et al.
(författare)
-
Search for flavor changing neutral currents in decays of top quarks
- 2011
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 701:3, s. 313-320
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Tidskriftsartikel (refereegranskat)abstract
- We present a search for flavor changing neutral currents in decays of top quarks. The analysis is based on a search for (ℓ,ℓ′=e,μ) final states using 4.1 fb−1 of integrated luminosity of collisions at . We extract limits on the branching ratio B(t→Zq) (q=u,c quarks), assuming anomalous tuZ or tcZ couplings. We do not observe any sign of such anomalous coupling and set a limit of B<3.2% at 95% C.L.
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70. |
- Abazov, V. M., et al.
(författare)
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Search for Higgs bosons decaying to tau(+)tau(-) pairs in p(p)over-bar collisions at root s=1.96 TeV
- 2012
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 707:3-4, s. 323-329
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Tidskriftsartikel (refereegranskat)abstract
- We present a search for the production of neutral Higgs bosons decaying into tau(+)tau(-) pairs in p (p) over bar collisions at a center-of-mass energy of 1.96 TeV. The data, corresponding to an integrated luminosity of 5.4 fb(-1), were collected by the DO experiment at the Fermilab Tevatron Collider. We set upper limits at the 95% C.L. on the product of production cross section and branching ratio for a scalar resonance decaying into tau(+)tau(-) pairs, and we interpret these limits as limits on the production of Higgs bosons in the minimal supersymmetric standard model (MSSM) and as constraints in the MSSM parameter space.
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