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Träfflista för sökning "WFRF:(Haley C. S.) ;pers:(Fox H.);lar1:(kth);pers:(Bernhard R.)"

Sökning: WFRF:(Haley C. S.) > Fox H. > Kungliga Tekniska Högskolan > Bernhard R.

  • Resultat 61-70 av 110
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61.
  • Abazov, V. M., et al. (författare)
  • Measurement of sigma(p(p)over-bar -> Z plus X)Br(Z -> tau(+)tau(-)) at root s=1.96 TeV
  • 2009
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 670:4-5, s. 292-299
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a measurement of the cross section for Z boson production times the branching fraction to tau lepton pairs sigma(p (p) over bar -> Z + X)Br(Z -> tau(+)tau(-)) in p (p) over bar collisions at root s = 1.96 TeV. The measurement is performed in the channel in which one tau lepton decays into a muon and neutrinos. and the other tau lepton decays hadronically or into an electron and neutrinos. The data sample corresponds to an integrated luminosity of 1.0 fb(-1) collected with the DO detector at the Fermilab Tevatron Collider. The sample contains 1511 candidate events with an estimated 20% background from jets or muons misidentified as tau leptons. We obtain sigma . Br = 240 +/- 8 (star) +/- 12 (sys) +/- 15 (lum) pb, which is consistent with the standard model prediction.
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62.
  • Abazov, V. M., et al. (författare)
  • Search for Neutral Higgs Bosons at High tan beta in the b(h/H/A) -> b tau(+)tau(-) Channel
  • 2009
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:5, s. 051804-:102, s. 051804-
  • Tidskriftsartikel (refereegranskat)abstract
    • The first search in p (p) over bar collisions at root s = 1.96 TeV for the production of neutral Higgs bosons in association with bottom quarks and decaying in two tau leptons is presented. The cross section for this process is enhanced in many extensions of the standard model, such as its minimal supersymmetric extension (MSSM) at large tan beta. The data, corresponding to an integrated luminosity of 328 pb(-1), were collected with the D0 detector at the Fermilab Tevatron Collider. An upper limit is set on the production cross section of neutral Higgs bosons in the mass range of 90 to 150 GeV, and this limit is used to exclude part of the MSSM parameter space.
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63.
  • Abazov, V. M., et al. (författare)
  • Search for Anomalous Top-Quark Couplings with the D0 Detector
  • 2009
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:9, s. 092002-
  • Tidskriftsartikel (refereegranskat)abstract
    • Anomalous Wtb couplings modify the angular correlations of the top-quark decay products and change the single top-quark production cross section. We present limits on anomalous top-quark couplings by combining information from W boson helicity measurements in top-quark decays and anomalous coupling searches in the single top-quark final state. We set limits on right-handed vector couplings as well as left-handed and right-handed tensor couplings based on about 1 fb(-1) of data collected by the D0 experiment.
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64.
  • Abazov, V. M., et al. (författare)
  • Search for pair production of second generation scalar leptoquarks
  • 2009
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 671:2, s. 224-232
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on a search for the pair production of second generation scalar leptoquarks (LQ) in p (p) over bar collisions at the center of mass energy root s- = 1.96 TeV using a data set corresponding to an integrated luminosity of 1.0 fb(-1) collected with the D empty set experiment at the Fermilab Tevatron Collider. Topologies arising from the LQ (LQ) over bar -> mu q nu q and LQ (LQ) over bar -> mu q mu q decay modes are investigated. No excess of data over the standard model prediction is observed and upper limits on the leptoquark pair production cross section are derived at the 95% C.L. as a function of the leptoquark mass and the branching fraction beta for the decay LQ -> mu q. These are interpreted as lower limits on the leptoquark mass as a function of beta. For beta = 1 (0.5), scalar second generation leptoquarks with masses up to 316 GeV (270 GeV) are excluded.
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65.
  • Abazov, V. M., et al. (författare)
  • 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
  • Ingår i: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 1550-7998 .- 1550-2368. ; 82:1, s. 012003-
  • 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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66.
  • Abazov, V. M., et al. (författare)
  • Measurement of the t-channel single top quark production cross section
  • 2010
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 682:4-5, s. 363-369
  • 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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67.
  • Abazov, V. M., et al. (författare)
  • Measurement of the top quark mass in final states with two leptons
  • 2009
  • Ingår i: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 1550-7998 .- 1550-2368. ; 80, s. 092006-
  • Tidskriftsartikel (refereegranskat)abstract
    • We present measurements of the top quark mass (m(t)) in tt candidate events with two final state leptons using 1 fb(-1) of data collected by the D0 experiment. Our data sample is selected by requiring two fully identified leptons or by relaxing one lepton requirement to an isolated track if at least one jet is tagged as a b jet. The top quark mass is extracted after reconstructing the event kinematics under the tt hypothesis using two methods. In the first method, we integrate over expected neutrino rapidity distributions, and in the second we calculate a weight for the possible top quark masses based on the observed particle momenta and the known parton distribution functions. We analyze 83 candidate events in the data and obtain m(t)=176.2 +/- 4.8(stat)+/- 2.1(sys) GeV and m(t)=173.2 +/- 4.9(stat)+/- 2.0(sys) GeV for the two methods, respectively. Accounting for correlations between the two methods, we combine the measurements to obtain m(t)=174.7 +/- 4.4(stat)+/- 2.0(sys) GeV.
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68.
  • Abazov, V. M., et al. (författare)
  • Measurement of Z/gamma* plus jet plus X angular distributions in p(p)over-bar collisions at root s=1.96 TeV
  • 2010
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 682:4-5, s. 370-380
  • 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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69.
  • Abazov, V. M., et al. (författare)
  • Search for charged Higgs bosons in top quark decays
  • 2009
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 682:3, s. 278-286
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a search for charged Higgs bosons in top quark decays. We analyze the e + jets, mu + jets, ee, e mu, mu mu, tau e and tau mu final states from top quark pair production events, using data from about 1 fb (1) of integrated luminosity recorded by the DO experiment at the Fermilab Tevatron Collider. We consider different scenarios of possible charged Higgs boson decays, one where the charged Higgs boson decays purely hadronically into a charm and a strange quark, another where it decays into a tau lepton and a tau neutrino and a third one where both decays appear. We extract limits on the branching ratio B(t -> H(+)b) for all these models. We use two methods, one where the t (t) over bar production cross section is fixed, and one where the cross section is fitted simultaneously with B(t -> H(+)b). Based on the extracted limits, we exclude regions in the charged Higgs boson mass and tan beta parameter space for different scenarios of the minimal supersymmetric standard model.
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70.
  • Abazov, V. M., et al. (författare)
  • Search for single top quarks in the tau plus jets channel using 4.8 fb(-1) of p(p)over-bar collision data
  • 2010
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 690:1, s. 5-14
  • 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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  • Resultat 61-70 av 110
Typ av publikation
tidskriftsartikel (110)
Typ av innehåll
refereegranskat (110)
Författare/redaktör
Abbott, B. (110)
Strandberg, Jonas (110)
Begel, M. (110)
Borissov, G. (110)
Brandt, A. (110)
Brock, R. (110)
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Brooijmans, G. (110)
Burdin, S. (110)
Calvet, S. (110)
Chakraborty, D. (110)
Cooke, M. (110)
De, K. (110)
Duflot, L. (110)
Fiedler, F. (110)
Gillberg, D. (110)
Haas, A. (110)
Han, L. (110)
Hensel, C. (110)
Kehoe, R. (110)
Kupco, A. (110)
Kvita, J. (110)
Lammers, S. (110)
Meyer, J. (110)
Piegaia, R. (110)
Pleier, M. -A. (110)
Qian, J. (110)
Rijssenbeek, M. (110)
Sawyer, L. (110)
Schwanenberger, C. (110)
Schwienhorst, R. (110)
Severini, H. (110)
Shabalina, E. (110)
Snyder, S. (110)
Sopczak, A. (110)
Sosebee, M. (110)
Spurlock, B. (110)
Stark, J. (110)
Strandberg, J. (110)
Strauss, M. (110)
Taylor, W. (110)
Tsybychev, D. (110)
Watts, G. (110)
White, A. (110)
Wicke, D. (110)
Yacoob, S. (110)
Zhu, J. (110)
Buescher, V. (110)
Gris, Ph. (110)
Haley, J. (110)
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Uppsala universitet (110)
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Engelska (110)
Forskningsämne (UKÄ/SCB)
Naturvetenskap (110)

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