| 1. |
- Abazov, V. M., et al.
(author)
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Forward-backward asymmetry in top quark-antiquark production
- 2011
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In: Physical Review D. - 1550-7998 .- 1550-2368. ; 84:11, s. 112005-
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Journal article (peer-reviewed)abstract
- We present a measurement of forward-backward asymmetry in top quark-antiquark production in proton-antiproton collisions in the final state containing a lepton and at least four jets. Using a data set corresponding to an integrated luminosity of 5.4 fb(-1), collected by the D0 experiment at the Fermilab Tevatron Collider, we measure the t (t) over bar forward-backward asymmetry to be (9.2 +/- 3.7)% at the reconstruction level. When corrected for detector acceptance and resolution, the asymmetry is found to be (19.6 +/- 6.5)%. We also measure a corrected asymmetry based on the lepton from a top quark decay, found to be (15.2 +/- 4.0)%. The results are compared to predictions based on the next-to-leading-order QCD generator MC@NLO. The sensitivity of the measured and predicted asymmetries to the modeling of gluon radiation is discussed.
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| 2. |
- Abazov, V. M., et al.
(author)
-
Measurement of leptonic asymmetries and top-quark polarization in t(t)over-bar production
- 2013
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In: Physical Review D. - 1550-7998 .- 1550-2368. ; 87:1, s. 011103-
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Journal article (peer-reviewed)abstract
- We present measurements of lepton (l) angular distributions in top-quark (t) pair production and t (t) over bar -> W(+)bW-(b) over bar -> l(+) vbl-(v) over bar(b) over bar decays produced in p (p) over bar collisions at a center-of-mass energy of root s = 1.96 TeV, where l is an electron or muon. Using data corresponding to an integrated luminosity of 5.4 fb(-1), collected with the D0 detector at the Fermilab Tevatron Collider, we measure for the first time the leptonic forward-backward asymmetry in dilepton final states and obtain A(FB)(l) = (5.8 +/- 5.1(stat) +/- 1.3(syst))%, corrected for detector acceptance. This is compared to the standard model prediction of A(FB)(l)(predicted) = (4.7 +/- 0.1)%. A deviation from the standard model prediction as previously seen in a D0 measurement based on the analysis of the l + jets final state is not observed in these dilepton final states. The two results differ from each other by 1.4 standard deviations and are combined to obtain A(FB)(l) = (11.8 +/- 3.2)%. Furthermore, we present a first study of the top-quark polarization.
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| 3. |
- Abazov, V. M., et al.
(author)
-
Measurement of the forward-backward asymmetry in the distribution of leptons in t(t)over-bar events in the lepton plus jets channel
- 2014
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In: Physical Review D. - 1550-7998 .- 1550-2368. ; 90:7, s. 072001-
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Journal article (peer-reviewed)abstract
- We present measurements of the forward-backward asymmetry in the angular distribution of leptons from decays of top quarks and antiquarks produced in proton-antiproton collisions. We consider the final state containing a lepton and at least three jets. The entire sample of data collected by the D0 experiment during Run II of the Fermilab Tevatron Collider, corresponding to 9.7 fb(-1) of integrated luminosity, is used. The asymmetry measured for reconstructed leptons is A(FB)(l) = (2.9 +/- 2.1(stat.)(-1.7)(+1.5) (syst.))%. When corrected for efficiency and resolution effects within the lepton rapidity coverage of vertical bar y(l)vertical bar < 1.5, the asymmetry is found to be A(FB)(l) = (4.2 +/- 2.3(stat.)(-2.0)(+1.7) (syst.))%. We examine the dependence of A(FB)(l) on the transverse momentum and rapidity of the lepton. Combination with the asymmetry measured in the final states containing two leptons yields A(FB)(l) = (4.2 +/- 2.0(stat.) +/- 1.4(syst.))%. The results are in agreement with predictions from the next-to-leading-order QCD generator MC@NLO, which predicts an asymmetry of A(FB)(l) = 2.0% for vertical bar y(l)vertical bar < 1.5.
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| 4. |
- Abazov, V. M., et al.
(author)
-
Measurement of the forward-backward asymmetry in top quark-antiquark production in p(p)over-bar collisions using the lepton plus jets channel
- 2014
-
In: Physical Review D. - 1550-7998 .- 1550-2368. ; 90:7
-
Journal article (peer-reviewed)abstract
- We present a measurement of the forward-backward asymmetry in top quark-antiquark production using the full Tevatron Run II data set collected by the D0 experiment at Fermilab. The measurement is performed in lepton + jets final states using a new kinematic fitting algorithm for events with four or more jets and a new partial reconstruction algorithm for events with only three jets. Corrected for detector acceptance and resolution effects, the asymmetry is evaluated to be A(FB) = (10.6 +/- 3.0)%. Results are consistent with the standard model predictions which range from 5.0% to 8.8%. We also present the dependence of the asymmetry on the invariant mass of the top quark-antiquark system and the difference in rapidities of the top quark and antiquark.
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