| 1. |
- Aad, G, et al.
(författare)
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Measurements of fiducial cross-sections for [Formula: see text] production with one or two additional b-jets in pp collisions at [Formula: see text]=8 TeV using the ATLAS detector.
- 2016
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 76
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Tidskriftsartikel (refereegranskat)abstract
- Fiducial cross-sections for [Formula: see text] production with one or two additional b-jets are reported, using an integrated luminosity of 20.3 fb[Formula: see text] of proton-proton collisions at a centre-of-mass energy of 8 TeV at the Large Hadron Collider, collected with the ATLAS detector. The cross-section times branching ratio for [Formula: see text] events with at least one additional b-jet is measured to be 950 [Formula: see text] 70 (stat.) [Formula: see text] (syst.) fb in the lepton-plus-jets channel and 50 [Formula: see text] 10 (stat.) [Formula: see text] (syst.) fb in the [Formula: see text] channel. The cross-section times branching ratio for events with at least two additional b-jets is measured to be 19.3 [Formula: see text] 3.5 (stat.) [Formula: see text] 5.7 (syst.) fb in the dilepton channel ([Formula: see text], [Formula: see text], and ee) using a method based on tight selection criteria, and 13.5 [Formula: see text] 3.3 (stat.) [Formula: see text] 3.6 (syst.) fb using a looser selection that allows the background normalisation to be extracted from data. The latter method also measures a value of 1.30 [Formula: see text] 0.33 (stat.) [Formula: see text] 0.28 (syst.)% for the ratio of [Formula: see text] production with two additional b-jets to [Formula: see text] production with any two additional jets. All measurements are in good agreement with recent theory predictions.
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| 2. |
- Aad, G, et al.
(författare)
-
Searches for scalar leptoquarks in pp collisions at [Formula: see text] = 8 TeV with the ATLAS detector.
- 2016
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 76
-
Tidskriftsartikel (refereegranskat)abstract
- Searches for pair-produced scalar leptoquarks are performed using 20 fb[Formula: see text] of proton-proton collision data provided by the LHC and recorded by the ATLAS detector at [Formula: see text] TeV. Events with two electrons (muons) and two or more jets in the final state are used to search for first (second)-generation leptoquarks. The results from two previously published ATLAS analyses are interpreted in terms of third-generation leptoquarks decaying to [Formula: see text] and [Formula: see text] final states. No statistically significant excess above the Standard Model expectation is observed in any channel and scalar leptoquarks are excluded at 95 % CL with masses up to [Formula: see text] 1050 GeV for first-generation leptoquarks, [Formula: see text] 1000 GeV for second-generation leptoquarks, [Formula: see text] 625 GeV for third-generation leptoquarks in the [Formula: see text] channel, and 200 [Formula: see text] 640 GeV in the [Formula: see text] channel.
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| 3. |
- Aad, G., et al.
(författare)
-
- 2016
-
Ingår i: Journal of High Energy Physics. - : Springer. - 1029-8479 .- 1126-6708. ; :1
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Tidskriftsartikel (refereegranskat)
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| 4. |
- Aad, G., et al.
(författare)
-
- 2016
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Ingår i: Physical Review D. Particles and fields. - : American Physical Society. - 0556-2821 .- 1089-4918. ; 93:1
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Tidskriftsartikel (refereegranskat)
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| 5. |
- Aad, G., et al.
(författare)
-
- 2015
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Ingår i: Journal of High Energy Physics. - : Springer. - 1029-8479 .- 1126-6708. ; :12
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Tidskriftsartikel (refereegranskat)
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| 6. |
- Aad, G., et al.
(författare)
-
- 2015
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Ingår i: Physical Review D. Particles and fields. - : American Physical Society. - 0556-2821 .- 1089-4918. ; 92:9
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Tidskriftsartikel (refereegranskat)
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| 7. |
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| 8. |
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| 9. |
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| 10. |
- Aad, G., et al.
(författare)
-
- 2015
-
Ingår i: Physical Review D. Particles and fields. - : American Physics Society. - 0556-2821 .- 1089-4918. ; 92:11
-
Tidskriftsartikel (refereegranskat)
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| 11. |
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| 12. |
- Aad, G., et al.
(författare)
-
- 2015
-
Ingår i: Journal of High Energy Physics. - : Springer. - 1029-8479 .- 1126-6708. ; :11
-
Tidskriftsartikel (refereegranskat)
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| 13. |
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| 14. |
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| 15. |
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| 16. |
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| 17. |
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| 18. |
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| 19. |
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| 20. |
- Aad, G., et al.
(författare)
-
- 2016
-
Ingår i: The European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6052. ; 76:1
-
Tidskriftsartikel (refereegranskat)
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| 21. |
- Aad, G., et al.
(författare)
-
- 2015
-
Tidskriftsartikel (refereegranskat)
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| 22. |
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| 23. |
- Aad, G., et al.
(författare)
-
- 2015
-
Tidskriftsartikel (refereegranskat)
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| 24. |
- Aad, G., et al.
(författare)
-
- 2015
-
Ingår i: The European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6052. ; 75:9
-
Tidskriftsartikel (refereegranskat)
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| 25. |
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| 26. |
- 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
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 104:6, s. 061802-
-
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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| 27. |
- Abazov, V. M., et al.
(författare)
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The upgraded DO detector
- 2006
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 565:2, s. 463-537
-
Tidskriftsartikel (refereegranskat)abstract
- The DO experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996. Since then, the detector has been upgraded to take advantage of improvements to the Tevatron and to enhance its physics capabilities. We describe the new elements of the detector, including the silicon microstrip tracker, central fiber tracker, solenoidal magnet, preshower detectors, forward muon detector, and forward proton detector. The uranium/liquid -argon calorimeters and central muon detector, remaining from Run 1, are discussed briefly. We also present the associated electronics, triggering, and data acquisition systems, along with the design and implementation of software specific to DO.
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| 28. |
- Aaltonen, T., et al.
(författare)
-
Evidence for a Particle Produced in Association with Weak Bosons and Decaying to a Bottom-Antibottom Quark Pair in Higgs Boson Searches at the Tevatron
- 2012
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 109:7, s. 071804-
-
Tidskriftsartikel (refereegranskat)abstract
- We combine searches by the CDF and D0 Collaborations for the associated production of a Higgs boson with a W or Z boson and subsequent decay of the Higgs boson to a bottom-antibottom quark pair. The data, originating from Fermilab Tevatron p (p) over bar collisions at root s = 1.96 TeV, correspond to integrated luminosities of up to 9.7 fb(-1). The searches are conducted for a Higgs boson with mass in the range 100-150 GeV/c(2). We observe an excess of events in the data compared with the background predictions, which is most significant in the mass range between 120 and 135 GeV/c(2). The largest local significance is 3.3 standard deviations, corresponding to a global significance of 3.1 standard deviations. We interpret this as evidence for the presence of a new particle consistent with the standard model Higgs boson, which is produced in association with a weak vector boson and decays to a bottom-antibottom quark pair.
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| 29. |
- Aaltonen, T., et al.
(författare)
-
Combination of CDF and D0 measurements of the W boson helicity in top quark decays
- 2012
-
Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 85:7, s. 071106-
-
Tidskriftsartikel (refereegranskat)abstract
- We report the combination of recent measurements of the helicity of the W boson from top quark decay by the CDF and D0 collaborations, based on data samples corresponding to integrated luminosities of 2.7-5.4 fb(-1) of p (p) over bar collisions collected during Run II of the Fermilab Tevatron collider. Combining measurements that simultaneously determine the fractions of W bosons with longitudinal (f(0)) and right-handed (f(+)) helicities, we find f(0) = 0.722 +/- 0.081[+/- 0.062(stat) +/- 0.052(syst)] and f(+) = -0.033 +/- 0.046[+/- 0.034(stat) +/- 0.031(syst)]. Combining measurements where one of the helicity fractions is fixed to the value expected in the standard model, we find f(0) = 0.682 +/- 0.057[+/- 0.035(stat) +/- 0.046(syst)] for fixed f(+) and f(+) = -0.015 +/- 0.035[+/- 0.018(stat) +/- 0.030(syst)] for fixed f(0). The results are consistent with standard model expectations.
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| 30. |
- Aaltonen, T., et al.
(författare)
-
Tevatron Run II combination of the effective leptonic electroweak mixing angle
- 2018
-
Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 97:11
-
Tidskriftsartikel (refereegranskat)abstract
- Drell-Yan lepton pairs produced in the process p (p) over bar -> l(+)l(-) + X through an intermediate gamma*/Z boson have an asymmetry in their angular distribution related to the spontaneous symmetry breaking of the electroweak force and the associated mixing of its neutral gauge bosons. The CDF and D0 experiments have measured the effective-leptonic electroweak mixing parameter sin(2) theta(lept)(eff) using electron and muon pairs selected from the full Tevatron proton-antiproton data sets collected in 2001-2011, corresponding to 9-10 fb(-1) of integrated luminosity. The combination of these measurements yields the most precise result from hadron colliders, sin(2)theta(lept)(eff) = 0.23148 +/- 0.00033. This result is consistent with, and approaches in precision, the best measurements from electron-positron colliders. The standard model inference of the on-shell electroweak mixing parameter sin(2) theta(W), or equivalently the W-boson mass M-W, using the ZFITTER software package yields sin(2) theta(W) = 0.22324 +/- 0.00033 or equivalently, M-W = 80.367 +/- 0.017 GeV/c(2).
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| 31. |
- Aaltonen, T., et al.
(författare)
-
Combined Forward-Backward Asymmetry Measurements in Top-Antitop Quark Production at the Tevatron
- 2018
-
Ingår i: Physical Review Letters. - : AMER PHYSICAL SOC. - 0031-9007 .- 1079-7114. ; 120:4
-
Tidskriftsartikel (refereegranskat)abstract
- The CDF and D0 experiments at the Fermilab Tevatron have measured the asymmetry between yields of forward- and backward-produced top and antitop quarks based on their rapidity difference and the asymmetry between their decay leptons. These measurements use the full data sets collected in proton-antiproton collisions at a center-of-mass energy of root s = 1.96 TeV. We report the results of combinations of the inclusive asymmetries and their differential dependencies on relevant kinematic quantities. The combined inclusive asymmetry is A(FB)(t (t) over bar) = 0.128 +/- 0.025. The combined inclusive and differential asymmetries are consistent with recent standard model predictions.
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| 32. |
- Aaltonen, T., et al.
(författare)
-
Observation of s-Channel Production of Single Top Quarks at the Tevatron
- 2014
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 112:23
-
Tidskriftsartikel (refereegranskat)abstract
- We report the first observation of single-top-quark production in the s channel through the combination of the CDF and D0 measurements of the cross section in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV. The data correspond to total integrated luminosities of up to 9.7 fb(-1) per experiment. The measured cross section is sigma(s) = 1.29(-0.24)(+0.26) pb. The probability of observing a statistical fluctuation of the background to a cross section of the observed size or larger is 1.8 x 10(-10), corresponding to a significance of 6.3 standard deviations for the presence of an s-channel contribution to the production of single-top quarks.
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| 33. |
- Aaltonen, T., et al.
(författare)
-
Tevatron Combination of Single-Top-Quark Cross Sections and Determination of the Magnitude of the Cabibbo-Kobayashi-Maskawa Matrix Element V-tb
- 2015
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 115:15
-
Tidskriftsartikel (refereegranskat)abstract
- We present the final combination of CDF and D0 measurements of cross sections for single-top-quark production in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV. The data correspond to total integrated luminosities of up to 9.7 fb(-1) per experiment. The t-channel cross section is measured to be sigma(t) = 2.25(-0.31)(+0.29) pb. We also present the combinations of the two-dimensional measurements of the s- vs t-channel cross section. In addition, we give the combination of the s + t channel cross section measurement resulting in sigma(s+t) = 3.30(-0.40)(+0.52) pb, without assuming the standard model value for the ratio sigma(s)/sigma(t). The resulting value of the magnitude of the top-to-bottom quark coupling is vertical bar V-tb vertical bar = 1.02(-0.05)(+0.06), corresponding to vertical bar V-tb vertical bar > 0.92 at the 95% C. L.
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| 34. |
- Aaltonen, T., et al.
(författare)
-
Tevatron Constraints on Models of the Higgs Boson with Exotic Spin and Parity Using Decays to Bottom-Antibottom Quark Pairs
- 2015
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 114:15
-
Tidskriftsartikel (refereegranskat)abstract
- Combined constraints from the CDF and D0 Collaborations on models of the Higgs boson with exotic spin J and parity P are presented and compared with results obtained assuming the standard model value J(P) = 0(+). Both collaborations analyzed approximately 10 fb(-1) of proton-antiproton collisions with a center-of-mass energy of 1.96 TeV collected at the Fermilab Tevatron. Two models predicting exotic Higgs bosons with J(P) = 0(-) and J(P) = 2(+) are tested. The kinematic properties of exotic Higgs boson production in association with a vector boson differ from those predicted for the standard model Higgs boson. Upper limits at the 95% credibility level on the production rates of the exotic Higgs bosons, expressed as fractions of the standard model Higgs boson production rate, are set at 0.36 for both the J(P) = 0(-) hypothesis and the J(P) = 2(+) hypothesis. If the production rate times the branching ratio to a bottom-antibottom pair is the same as that predicted for the standard model Higgs boson, then the exotic bosons are excluded with significances of 5.0 standard deviations and 4.9 standard deviations for the J(P) = 0(-) and J(P) = 2(+) hypotheses, respectively.
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| 35. |
- Aaltonen, T., et al.
(författare)
-
Combination of CDF and D0 W-Boson mass measurements
- 2013
-
Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 88:5, s. 052018-
-
Tidskriftsartikel (refereegranskat)abstract
- We summarize and combine direct measurements of the mass of the W boson in root s = 1.96 TeV proton-antiproton collision data collected by CDF and D0 experiments at the Fermilab Tevatron Collider. Earlier measurements from CDF and D0 are combined with the two latest, more precise measurements: a CDF measurement in the electron and muon channels using data corresponding to 2.2 fb(-1) of integrated luminosity, and a D0 measurement in the electron channel using data corresponding to 4.3 fb(-1) of integrated luminosity. The resulting Tevatron average for the mass of the W boson is M-W = 80387 +/- 16 MeV. Including measurements obtained in electron-positron collisions at LEP yields the most precise value of M-W = 80385 +/- 15 MeV.
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| 36. |
- Aaltonen, T., et al.
(författare)
-
Combination of measurements of the top-quark pair production cross section from the Tevatron Collider
- 2014
-
Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 89:7
-
Tidskriftsartikel (refereegranskat)abstract
- We combine six measurements of the inclusive top-quark pair (t(sic)) production cross section (sigma(t)(sic)) from data collected with the CDF and D0 detectors at the Fermilab Tevatron with proton-antiproton collisions at root s = 1.96 TeV. The data correspond to integrated luminosities of up to 8.8 fb(-1). We obtain a value of sigma tt = 7.60 +/- 0.41 pb for a top-quark mass of m(t) = 172.5 GeV. The contributions to the uncertainty are 0.20 pb from statistical sources, 0.29 pb from systematic sources, and 0.21 pb from the uncertainty on the integrated luminosity. The result is in good agreement with the standard model expectation of 7.35(-0.33)(+0.28) pb at next-to-next-to-leading order and next-to-next-to leading logarithms in perturbative QCD.
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| 37. |
- Aaltonen, T., et al.
(författare)
-
Higgs boson studies at the Tevatron
- 2013
-
Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 88:5, s. 052014-
-
Tidskriftsartikel (refereegranskat)abstract
- We combine searches by the CDF and D0 Collaborations for the standard model Higgs boson with mass in the range 90-200 GeV/c(2) produced in the gluon-gluon fusion, WH, ZH, t (t) over barH, and vector boson fusion processes, and decaying in the H -> b (b) over bar, H -> W+W-, H -> ZZ, H -> tau(+)tau(-), and H -> gamma gamma modes. The data correspond to integrated luminosities of up to 10 fb(-1) and were collected at the Fermilab Tevatron in p (p) over bar collisions at root s = 1.96 TeV. The searches are also interpreted in the context of fermiophobic and fourth generation models. We observe a significant excess of events in the mass range between 115 and 140 GeV/c(2). The local significance corresponds to 3.0 standard deviations at m(H) = 125 GeV/c(2), consistent with the mass of the Higgs boson observed at the LHC, and we expect a local significance of 1.9 standard deviations. We separately combine searches for H -> b (b) over bar, H -> W+W-, H -> tau(+)tau(-), and H -> gamma gamma. The observed signal strengths in all channels are consistent with the presence of a standard model Higgs boson with a mass of 125 GeV/c(2).
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| 38. |
- Abazov, V. M., et al.
(författare)
-
Evidence for production of single top quarks and first direct measurement of vertical bar V-tb vertical bar
- 2007
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 98:18, s. 181802-
-
Tidskriftsartikel (refereegranskat)abstract
- The D0 Collaboration presents first evidence for the production of single top quarks at the Fermilab Tevatron < p(p)over bar > collider. Using a 0.9 fb(-1) dataset, we apply a multivariate analysis to separate signal from background and measure sigma(< p(p)over bar >-> tb+X,tqb+X)=4.9 +/- 1.4 pb. The probability to measure a cross section at this value or higher in the absence of a signal is 0.035%, corresponding to a 3.4 standard deviation significance. We use the cross section measurement to directly determine the Cabibbo-Kobayashi-Maskawa matrix element that describes the Wtb coupling and find 0.68 <= 1 at 95% C.L. within the standard model.
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| 39. |
- Abazov, V. M., et al.
(författare)
-
Experimental discrimination between charge 2e/3 top quark and charge 4e/3 exotic quark production scenarios
- 2007
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 98:4, s. 041801-
-
Tidskriftsartikel (refereegranskat)abstract
- We present the first experimental discrimination between the 2e/3 and 4e/3 top quark electric charge scenarios, using top quark pairs (t (t) over bar) produced in p (p) over bar collisions at root s =1.96 TeV by the Fermilab Tevatron Collider. We use 370 pb(-1) of data collected by the D0 experiment and select events with at least one high transverse momentum electron or muon, high transverse energy imbalance, and four or more jets. We discriminate between b- and (b) over bar -quark jets by using the charge and momenta of tracks within the jet cones. The data are consistent with the expected electric charge, |q|=2e/3. We exclude, at the 92% C.L., that the sample is solely due to the production of exotic quark pairs Q (Q) over bar with |q|=4e/3. We place an upper limit on the fraction of Q (Q) over bar pairs rho < 0.80 at the 90% C.L.
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| 40. |
- Abazov, V. M., et al.
(författare)
-
Limits on anomalous trilinear gauge couplings from WW -> e(+)e(-), WW -> e(+/-)mu(-/+), and WW ->mu(+)mu(-) events from pp collisions at root s=1.96 TeV
- 2006
-
Ingår i: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 1550-7998 .- 1550-2368. ; 74:5, s. 057101-
-
Tidskriftsartikel (refereegranskat)abstract
- Limits are set on anomalous WW gamma and WWZ trilinear gauge couplings using W+W--> e(+)nu(e)e(-)(nu) over bar (e), W+W--> e(+/-)nu(e)mu(-/+)nu(mu), and W+W-->mu(+)nu(mu)mu(-)(nu) over bar (mu) events. The data set was collected by the Run II D0 detector at the Fermilab Tevatron Collider and corresponds to approximately 250 pb(-1) of integrated luminosity at root s=1.96 TeV. Under the assumption that the WW gamma couplings are equal to the WWZ couplings and using a form factor scale of Lambda=2.0 TeV, the combined 95% C.L. one-dimensional coupling limits from all three channels are -0.32
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| 41. |
- Abazov, V. M., et al.
(författare)
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Measurement of the CP-violation parameter of B-0 mixing and decay with p(p)over-bar ->mu mu X data
- 2006
-
Ingår i: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 1550-7998 .- 1550-2368. ; 74:9, s. 092001-
-
Tidskriftsartikel (refereegranskat)abstract
- We measure the dimuon charge asymmetry A in p (p) over bar collisions at a center of mass energy root s=1960 GeV. The data was recorded with the D0 detector and corresponds to an integrated luminosity of approximately 1.0 fb(-1). Assuming that the asymmetry A is due to asymmetric B-0 <->(B) over bar (0) mixing and decay, we extract the CP-violation parameter of B-0 mixing and decay: ((epsilon B0))/(1+vertical bar epsilon B0 vertical bar 2)=(AB0)/(4)= -0.0023 +/- 0.0011(stat)+/- 0.0008(syst).A(B)(0) is the dimuon charge asymmetry from decays of B-0(B) over bar (0) pairs. The general case, with CP violation in both B-0 and B-s(0) systems, is also considered. Finally we obtain the forward-backward asymmetry that quantifies the tendency of mu(+) to go in the proton direction and mu(-) to go in the antiproton direction. The results are consistent with the standard model and constrain new physics.
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| 42. |
- Abazov, V. M., et al.
(författare)
-
Measurement of the ratios of the Z/gamma*+ >= n jet production cross sections to the total inclusive Z/gamma* cross section in p(p)over-bar collisions at root s=1.96 TeV
- 2008
-
Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 658, s. 112-
-
Tidskriftsartikel (refereegranskat)abstract
- We present a study of events with Z bosons and associated jets produced at the Fermilab Tevatron collider in p p collisions at a center of mass energy of 1.96 TeV The data sample consists of nearly 14000 Z/gamma* -> e(+)e(-) candidates corresponding to an integrated luminosity of 0.4 fb(-1) collected with the D circle divide detector. Ratios of the Z/gamma*+ >= n jet cross sections to the total inclusive Z/gamma* cross section have been measured for n = 1-4 jets, and found to be in good agreement with a next-to-leading order QCD calculation and with a tree-level QCD prediction with parton shower simulation and hadronization.
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| 43. |
- Abazov, V. M., et al.
(författare)
-
Search for neutral, long-lived particles decaying into two muons in p(p)over-bar collisions at root s=1.96 TeV
- 2006
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 97:16, s. 161802-
-
Tidskriftsartikel (refereegranskat)abstract
- We present a search for a neutral particle, pair produced in pp collisions at root s=1.96 TeV, which decays into two muons and lives long enough to travel at least 5 cm before decaying. The analysis uses approximate to 380 pb(-1) of data recorded with the D0 detector. The background is estimated to be about one event. No candidates are observed, and limits are set on the pair-production cross section times branching fraction into dimuons + X for such particles. For a mass of 10 GeV and lifetime of 4x10(-11) s, we exclude values greater than 0.14 pb (95% C.L.). These results are used to limit the interpretation of NuTeV's excess of dimuon events.
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| 44. |
- Abazov, V. M., et al.
(författare)
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Search for pair production of scalar bottom quarks in p(p)over-bar collisions at root s = 1.96 TeV
- 2006
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 97:17, s. 171806-
-
Tidskriftsartikel (refereegranskat)abstract
- A search for direct production of scalar bottom quarks ((b) over bar) is performed with 310 pb(-1) of data collected by the D0 experiment in p (p) over bar collisions at root s = 1.96 TeV at the Fermilab Tevatron Collider. The topology analyzed consists of two b jets and an imbalance in transverse momentum due to undetected neutralinos (chi(0)(1)), with chi(0)(1) assumed to be the lightest supersymmetric particle. We find the data consistent with standard model expectations, and set a 95% C.L. exclusion domain in the (m(b), m(chi 1)(0)) mass plane, improving significantly upon the results from run I of the Tevatron.
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| 45. |
- Abazov, V. M., et al.
(författare)
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Measurement of B-d mixing using opposite-side flavor tagging
- 2006
-
Ingår i: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 1550-7998 .- 1550-2368. ; 74:11, s. 112002-
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Tidskriftsartikel (refereegranskat)abstract
- We report on a measurement of the B-d(0) mixing frequency and the calibration of an opposite-side flavor tagger in the D0 experiment. Various properties associated with the b quark on the opposite side of the reconstructed B meson are combined using a likelihood-ratio method into a single variable with enhanced tagging power. Its performance is tested with data, using a large sample of reconstructed semileptonic B ->mu(DX)-X-0 and B ->mu(DX)-X-* decays, corresponding to an integrated luminosity of approximately 1 fb(-1). The events are divided into groups depending on the value of the combined tagging variable, and an independent analysis is performed in each group. Combining the results of these analyses, the overall effective tagging power is found to be epsilon D-2=(2.48 +/- 0.21(-0.06)(+0.08))%. The measured B-d(0) mixing frequency Delta m(d)=0.506 +/- 0.020(stat)+/- 0.016(syst) ps(-1) is in good agreement with the world average value.
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| 46. |
- Abazov, V. M., et al.
(författare)
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Measurement of the B-s(0) lifetime using semileptonic decays
- 2006
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 97:24, s. 241801-
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Tidskriftsartikel (refereegranskat)abstract
- We report a measurement of the B-s(0) lifetime in the semileptonic decay channel B-s(0)-> D-s(-)mu(+)nu X (and its charge conjugate), using approximately 0.4 fb(-1) of data collected with the D0 detector during 2002-2004. Using 5176 reconstructed D-s(-)mu(+) signal events, we have measured the B-s(0) lifetime to be tau(B-s(0))=1.398 +/- 0.044(stat)(-0.025)(+0.028)(syst) ps. This is the most precise measurement of the B-s(0) lifetime to date.
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| 47. |
- Abazov, V. M., et al.
(författare)
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Measurement of the p(p)over-bar -> t(t)over-bar + X production cross section at root s=1.96 TeV in the fully hadronic decay channel
- 2007
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Ingår i: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 1550-7998. ; 76:7, s. 072007-
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Tidskriftsartikel (refereegranskat)abstract
- A measurement of the top quark pair production cross section in proton antiproton collisions at an interaction energy of root s=1.96 TeV is presented. This analysis uses 405 +/- 25 pb(-1) of data collected with the D0 detector at the Fermilab Tevatron Collider. Fully hadronic t (t) over bar decays with final states of six or more jets are separated from the multijet background using secondary vertex tagging and a neural network. The t (t) over bar cross section is measured as sigma(t (t) over bar)=4.5(-1.9)(+2.0)(stat)(-1.1)(+1.4)(syst)+/- 0.3(lumi) pb for a top quark mass of m(t)=175 GeV/c(2).
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| 48. |
- Abazov, V. M., et al.
(författare)
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Measurement of the top quark mass in the lepton plus jets final state with the matrix element method
- 2006
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Ingår i: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 1550-7998 .- 1550-2368. ; 74:9, s. 092005-
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Tidskriftsartikel (refereegranskat)abstract
- We present a measurement of the top quark mass with the matrix element method in the lepton+jets final state. As the energy scale for calorimeter jets represents the dominant source of systematic uncertainty, the matrix element likelihood is extended by an additional parameter, which is defined as a global multiplicative factor applied to the standard energy scale. The top quark mass is obtained from a fit that yields the combined statistical and systematic jet energy scale uncertainty. Using a data set of 0.4 fb(-1) taken with the D0 experiment at Run II of the Fermilab Tevatron Collider, the mass of the top quark is measured using topological information to be: m(top)(center dot+jets)(topo)=169.2(-7.4)(+5.0)(stat+JES)(-1.4)(+1.5)(syst) GeV, and when information about identified b jets is included: m(top)(center dot+jets)(b-tag)=170.3(-4.5)(+4.1)(stat+ JES)(-1.8)(+1.2)(syst) GeV. The measurements yield a jet energy scale consistent with the reference scale.
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| 49. |
- Abazov, V. M., et al.
(författare)
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Search for W ' boson production in the W ' -> t(b)over-bar decay channel
- 2006
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 641:6, s. 423-431
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Tidskriftsartikel (refereegranskat)abstract
- We present a search for the production of a new heavy gauge boson W' that decays to a top quark and a bottom quark. We have analyzed 230 pb(-1) of data collected with the DO detector at the Fermilab Tevatron collider at a center-of-mass energy of 1.96 TeV. No significant excess of events above the standard model expectation is found in any region of the final state invariant mass distribution. We set upper limits on the production cross section of W' bosons times branching ratio to top quarks at the 95% confidence level for several different W, boson masses. We exclude masses between 200 and 610 GeV for a W' boson with standard-model-like couplings, between 200 and 630 GeV for a W, boson with right-handed couplings that is allowed to decay to both leptons and quarks, and between 200 and 670 GeV for a W' boson with right-handed couplings that is only allowed to decay to quarks.
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| 50. |
- Abazov, V. M., et al.
(författare)
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Measurement of the t(t)over-bar production cross section in p(p)over-bar collisions at root s=1.96 TeV using secondary vertex b tagging
- 2006
-
Ingår i: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 1550-7998 .- 1550-2368. ; 74:11, s. 112004-
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Tidskriftsartikel (refereegranskat)abstract
- We report a new measurement of the t (t) over bar production cross section in p (beta) over bar collisions at a center-of-mass energy of 1.96 TeV using events with one charged lepton (electron or muon), missing transverse energy, and jets. Using 425 pb(-1) of data collected using the D0 detector at the Fermilab Tevatron Collider, and enhancing the t (t) over bar content of the sample by tagging b jets with a secondary vertex tagging algorithm, the t (t) over bar production cross section is measured to be sigma(p (t) over bar -> t (t) over bar +X)=6.6 +/- 0.9(stat+syst) +/- 0.4(lum) pb. This cross section is the most precise D0 measurement to date for t (t) over bar production and is in good agreement with standard model expectations.
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