| 1. |
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| 2. |
- Abdo, A. A., et al.
(författare)
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FERMI LARGE AREA TELESCOPE OBSERVATIONS OF THE VELA PULSAR
- 2009
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 696:2, s. 1084-1093
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Tidskriftsartikel (refereegranskat)abstract
- The Vela pulsar is the brightest persistent source in the GeV sky and thus is the traditional first target for new gamma-ray observatories. We report here on initial Fermi Large Area Telescope observations during verification phase pointed exposure and early sky survey scanning. We have used the Vela signal to verify Fermi timing and angular resolution. The high-quality pulse profile, with some 32,400 pulsed photons at E >= 0.03 GeV, shows new features, including pulse structure as fine as 0.3 ms and a distinct third peak, which shifts in phase with energy. We examine the high-energy behavior of the pulsed emission; initial spectra suggest a phase-averaged power-law index of Gamma = 1.51(-0.04)(+0.05) with an exponential cutoff at E-c = 2.9 +/- 0.1 GeV. Spectral fits with generalized cutoffs of the form e(-(E/Ec)b) require b <= 1, which is inconsistent with magnetic pair attenuation, and thus favor outer-magnetosphere emission models. Finally, we report on upper limits to any unpulsed component, as might be associated with a surrounding pulsar wind nebula.
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| 3. |
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| 4. |
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| 5. |
- Bombarda, F., et al.
(författare)
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Runaway electron beam control
- 2019
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 1361-6587 .- 0741-3335. ; 61:1
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Tidskriftsartikel (refereegranskat)
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| 6. |
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| 9. |
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| 15. |
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| 16. |
- Krasilnikov, A., et al.
(författare)
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Evidence of 9 Be + p nuclear reactions during 2ω CH and hydrogen minority ICRH in JET-ILW hydrogen and deuterium plasmas
- 2018
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 58:2
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Tidskriftsartikel (refereegranskat)abstract
- The intensity of 9Be + p nuclear fusion reactions was experimentally studied during second harmonic (2ω CH) ion-cyclotron resonance heating (ICRH) and further analyzed during fundamental hydrogen minority ICRH of JET-ILW hydrogen and deuterium plasmas. In relatively low-density plasmas with a high ICRH power, a population of fast H+ ions was created and measured by neutral particle analyzers. Primary and secondary nuclear reaction products, due to 9Be + p interaction, were observed with fast ion loss detectors, γ-ray spectrometers and neutron flux monitors and spectrometers. The possibility of using 9Be(p, d)2α and 9Be(p, α)6Li nuclear reactions to create a population of fast alpha particles and study their behaviour in non-active stage of ITER operation is discussed in the paper.
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| 17. |
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| 19. |
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| 20. |
- Murari, A., et al.
(författare)
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A control oriented strategy of disruption prediction to avoid the configuration collapse of tokamak reactors
- 2024
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Ingår i: Nature Communications. - 2041-1723 .- 2041-1723. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- The objective of thermonuclear fusion consists of producing electricity from the coalescence of light nuclei in high temperature plasmas. The most promising route to fusion envisages the confinement of such plasmas with magnetic fields, whose most studied configuration is the tokamak. Disruptions are catastrophic collapses affecting all tokamak devices and one of the main potential showstoppers on the route to a commercial reactor. In this work we report how, deploying innovative analysis methods on thousands of JET experiments covering the isotopic compositions from hydrogen to full tritium and including the major D-T campaign, the nature of the various forms of collapse is investigated in all phases of the discharges. An original approach to proximity detection has been developed, which allows determining both the probability of and the time interval remaining before an incoming disruption, with adaptive, from scratch, real time compatible techniques. The results indicate that physics based prediction and control tools can be developed, to deploy realistic strategies of disruption avoidance and prevention, meeting the requirements of the next generation of devices.
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| 21. |
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| 22. |
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| 23. |
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| 24. |
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| 25. |
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| 26. |
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- 2018
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 58:1
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Forskningsöversikt (refereegranskat)
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| 27. |
- Andreoni, I., et al.
(författare)
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Follow Up of GW170817 and Its Electromagnetic Counterpart by Australian-Led Observing Programmes
- 2017
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Ingår i: Publications Astronomical Society of Australia. - : Cambridge University Press (CUP). - 1323-3580 .- 1448-6083. ; 34
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Forskningsöversikt (refereegranskat)abstract
- The discovery of the first electromagnetic counterpart to a gravitational wave signal has generated follow-up observations by over 50 facilities world-wide, ushering in the new era of multi-messenger astronomy. In this paper, we present follow-up observations of the gravitational wave event GW170817 and its electromagnetic counterpart SSS17a/DLT17ck (IAU label AT2017gfo) by 14 Australian telescopes and partner observatories as part of Australian-based and Australian-led research programs. We report early- to late-time multi-wavelength observations, including optical imaging and spectroscopy, mid-infrared imaging, radio imaging, and searches for fast radio bursts. Our optical spectra reveal that the transient source emission cooled from approximately 6 400 K to 2 100 K over a 7-d period and produced no significant optical emission lines. The spectral profiles, cooling rate, and photometric light curves are consistent with the expected outburst and subsequent processes of a binary neutron star merger. Star formation in the host galaxy probably ceased at least a Gyr ago, although there is evidence for a galaxy merger. Binary pulsars with short (100 Myr) decay times are therefore unlikely progenitors, but pulsars like PSR B1534+12 with its 2.7 Gyr coalescence time could produce such a merger. The displacement (similar to 2.2 kpc) of the binary star system from the centre of the main galaxy is not unusual for stars in the host galaxy or stars originating in the merging galaxy, and therefore any constraints on the kick velocity imparted to the progenitor are poor.
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| 28. |
- 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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| 29. |
- Abazov, V. M., et al.
(författare)
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Azimuthal decorrelations and multiple parton interactions in gamma+2 jet and gamma+3 jet events in p(p)over-bar collisions at root s=1.96 TeV
- 2011
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Ingår i: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 1550-7998 .- 1550-2368. ; 83:5, s. 052008-
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Tidskriftsartikel (refereegranskat)abstract
- Samples of inclusive gamma + 2 jet and gamma + 3 jet events collected by the D0 experiment with an integrated luminosity of about 1 fb(-1) in p (p) over bar collisions at root s = 1.96 TeV are used to measure cross sections as a function of the angle in the plane transverse to the beam direction between the transverse momentum (p(T)) of the gamma + leading jet system (jets are ordered in p(T)) and p(T) of the other jet for gamma + 2 jet, or p(T) sum of the two other jets for gamma + 3 jet events. The results are compared to different models of multiple parton interactions (MPI) in the PYTHIA and SHERPA Monte Carlo (MC) generators. The data indicate a contribution from events with double parton (DP) interactions and are well-described by predictions provided by the PYTHIA MPI models with p(T)-ordered showers and by SHERPA with the default MPI model. The gamma + 2 jet data are also used to determine the fraction of events with DP interactions as a function of the azimuthal angle and as a function of the second jet p(T).
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| 30. |
- Abazov, V. M., et al.
(författare)
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b-Jet identification in the D0 experiment
- 2010
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 620:2-3, s. 490-517
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Tidskriftsartikel (refereegranskat)abstract
- Algorithms distinguishing jets originating from b quarks from other jet flavors are important tools in the physics program of the D0 experiment at the Fermilab Tevatron p (p) over bar collider. This article describes the methods that have been used to identify b-quark jets, exploiting in particular the long lifetimes of b-flavored hadrons, and the calibration of the performance of these algorithms based on collider data.
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| 31. |
- Abazov, V. M., et al.
(författare)
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Bounds on an Anomalous Dijet Resonance in W plus jets Production in p(p)over-bar Collisions at root s=1.96 TeV
- 2011
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 107:1, s. 011804-
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Tidskriftsartikel (refereegranskat)abstract
- We present a study of the dijet invariant mass spectrum in events with two jets produced in association with a W boson in data corresponding to an integrated luminosity of 4.3 fb(-1) collected with the D0 detector at root s = 1.96 TeV. We find no evidence for anomalous resonant dijet production and derive upper limits on the production cross section of an anomalous dijet resonance recently reported by the CDF Collaboration, investigating the range of dijet invariant mass from 110 to 170 GeV/c(2). The probability of the D0 data being consistent with the presence of a dijet resonance with 4 pb production cross section at 145 GeV/c(2) is 8 x 10(-6).
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| 32. |
- Abazov, V. M., et al.
(författare)
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Dependence of the t(t)over-bar production cross section on the transverse momentum of the top quark
- 2010
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 693:5, s. 515-521
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Tidskriftsartikel (refereegranskat)abstract
- We present a measurement of the differential cross section for t (t) over bar events produced in p (p) over bar collisions at root s = 1.96 TeV as a function of the transverse momentum (p(T)) of the top quark. The selected events contain a high-p(T) lepton (l), a large imbalance in p(T). four or more jets with at least one candidate for a b jet, and correspond to 1 fb(-1) of integrated luminosity recorded with the D0 detector. Objects in the event are associated through a constrained kinematic fit to the t (t) over bar -> WbW (b) over bar -> lvbq (q) over bar' (b) over bar process. Results from next and next-to-next-to-leading-order perturbative QCD calculations agree with the measured differential cross section. Comparisons are also provided to predictions from Monte Carlo event generators using QCD calculations at different levels of precision. (C) 2010 Elsevier B.V. All rights reserved.
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| 33. |
- Abazov, V. M., et al.
(författare)
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Determination of the pole and (MS)over-bar masses of the top quark from the t(t)over-bar cross section
- 2011
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 703:4, s. 422-427
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Tidskriftsartikel (refereegranskat)abstract
- We use higher-order quantum chromodynamics calculations to extract the mass of the top quark from the t (t) over bar cross section measured in the lepton + jets channel in p (p) over bar collisions at root s = 1.96 TeV using 5.3 fb(-1) of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron Collider. The extracted top quark pole mass and (MS) over bar mass are compared to the current Tevatron average top quark mass obtained from direct measurements.
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| 34. |
- Abazov, V. M., et al.
(författare)
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Determination of the strong coupling constant from the inclusive jet cross section in pp collisions at s=1.96 TeV
- 2009
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Ingår i: PHYS REV D. - 1550-7998 .- 1550-2368. ; 80, s. 111107-
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Tidskriftsartikel (refereegranskat)abstract
- We determine the strong coupling constant alpha(s) and its energy dependence from the p(T) dependence of the inclusive jet cross section in pp collisions at s=1.96 TeV. The strong coupling constant is determined over the transverse momentum range 50 < p(T)< 145 GeV. Using perturbative QCD calculations to order O(alpha(3)(s)) combined with O(alpha(4)(s)) contributions from threshold corrections, we obtain alpha(s)(M-Z)=0.1161(-0.0048)(+0.0041). This is the most precise result obtained at a hadron-hadron collider.
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| 35. |
- Abazov, V. M., et al.
(författare)
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Determination of the Width of the Top Quark
- 2011
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 106:2, s. 022001-
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Tidskriftsartikel (refereegranskat)abstract
- We extract the total width of the top quark, Gamma(t), from the partial decay width Gamma(t -> Wb) measured using the t-channel cross section for single top-quark production and from the branching fraction B(t -> Wb) measured in t (t) over bar t events using up to 2.3 fb(-1) of integrated luminosity collected by the D0 Collaboration at the Tevatron p (p) over bar Collider. The result is Gamma(t) = 1.99(-0.55)(+0.69) GeV, which translates to a top-quark lifetime of tau(t) = (3.3-(+1.3)(0.9)) x 10(-25) s. Assuming a high mass fourth generation b' quark and unitarity of the four-generation quark-mixing matrix, we set the first upper limit on vertical bar V-tb'vertical bar < 0.63 at 95% C.L.
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| 36. |
- Abazov, V. M., et al.
(författare)
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Direct measurement of the mass difference between top and antitop quarks
- 2011
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 84:5, s. 052005-
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Tidskriftsartikel (refereegranskat)abstract
- We present a direct measurement of the mass difference between top and antitop quarks (Delta m) in lepton + jets t (t) over bar final states using the "matrix element" method. The purity of the lepton + jets sample is enhanced for t (t) over bar events by identifying at least one of the jets as originating from a b quark. The analyzed data correspond to 3.6 fb(-1) of p (p) over bar collisions at root s = 1.96 TeV acquired by D0 in Run II of the Fermilab Tevatron Collider. The combination of the e + jets and mu + jets channels yields Delta m = 0.8 +/- 1.8(stat) +/- 0.5(syst) GeV, which is in agreement with the standard model expectation of no mass difference.
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| 37. |
- 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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| 38. |
- Abazov, V. M., et al.
(författare)
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Evidence for an anomalous like-sign dimuon charge asymmetry
- 2010
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Ingår i: Physical Review D. - 1550-7998. ; 82:13, s. 032001-
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Tidskriftsartikel (refereegranskat)abstract
- We measure the charge asymmetry A of like-sign dimuon events in 6.1 fb(-1) of p (p) over bar collisions recorded with the D0 detector at a center-of-mass energy root s = 1.96 TeV at the Fermilab Tevatron collider. From A, we extract the like-sign dimuon charge asymmetry in semileptonic b-hadron decays: A(sl)(b) = -0.00957 +/- 0.00251 (stat) +/- 0.00146 (syst). This result differs by 3.2 standard deviations from the standard model prediction A(sl)(b)(SM) = (-2.3(0.6)(+0.5)) x 10(-4) and provides first evidence of anomalous CP violation in the mixing of neutral B mesons.
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| 39. |
- Abazov, V. M., et al.
(författare)
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Evidence for an Anomalous Like-Sign Dimuon Charge Asymmetry
- 2010
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 105:8, s. 081801-
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Tidskriftsartikel (refereegranskat)abstract
- We measure the charge asymmetry A =(N++ -N--)/(N++ + N--) of like-sign dimuon events in 6.1 fb(-1) of p (p) over bar collisions recorded with the D0 detector at a center-of-mass energy root s = 1: 96 TeV at the Fermilab Tevatron collider. From A we extract the like-sign dimuon charge asymmetry in semileptonic b-hadron decays: A(sl)(b) = -0.009 57 +/- 0.00251(stat) +/- 0.001 46(sys). It differs by 3.2 standard deviations from the standard model prediction A(sl)(b)(SM) = (-2.3(-0.6)(+0.5)) x 10(-4), and provides first evidence of anomalous CP violation in the mixing of neutral B mesons.
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| 40. |
- Abazov, V. M., et al.
(författare)
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Evidence for the Decay B-s(0)->(DsDs(*))-D-(*) and a Measurement of Delta Gamma(CP)(s)/Gamma(s)
- 2009
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:9, s. 091801-
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Tidskriftsartikel (refereegranskat)abstract
- We search for the semi-inclusive process B-s(0)->(DsDs(*))-D-(*) using 2.8 fb(-1) of pp collisions at s=1.96 TeV recorded by the D0 detector operating at the Fermilab Tevatron Collider. We observe 26.6 +/- 8.4 signal events with a significance above background of 3.2 standard deviations yielding a branching ratio of B(B-s(0)->(DsDs(*))-D-(*))=0.035 +/- 0.010(stat.)+/- 0.011(syst.). Under certain theoretical assumptions, these double-charm final states saturate CP-even eigenstates in the B-s(0) decays resulting in a width difference of Delta Gamma(CP)(s)/Gamma(s)=0.072 +/- 0.021(stat.)+/- 0.022(syst.).
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| 41. |
- Abazov, V. M., et al.
(författare)
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Forward-backward asymmetry in top quark-antiquark production
- 2011
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 84:11, s. 112005-
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Tidskriftsartikel (refereegranskat)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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| 42. |
- Abazov, V. M., et al.
(författare)
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High mass exclusive diffractive dijet production in p(p)over-bar collisions at root s=1.96 TeV
- 2011
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 705:3, s. 193-199
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Tidskriftsartikel (refereegranskat)abstract
- We present evidence for diffractive exclusive dijet production with an invariant dijet mass greater than 100 GeV in data collected with the DO experiment at the Fermilab Tevatron Collider. A discriminant based on calorimeter information is used to measure a significant number of events with little energy (typically less than 10 GeV) outside the dijet system, consistent with the diffractive exclusive dijet production topology. The probability for these events to be explained by other dijet production processes is 2 x 10(-6), corresponding to a 4.7 standard deviation significance.
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| 43. |
- Abazov, V. M., et al.
(författare)
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Measurement of color flow in t(t)over-bar events from p(p)over-bar collisions at root s=1.96 TeV
- 2011
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Ingår i: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 1550-7998. ; 83:9, s. 092002-
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Tidskriftsartikel (refereegranskat)abstract
- We present the first measurement of the color representation of the hadronically decaying W boson in t (t) over bar events, from 5.3 fb(-1) of integrated luminosity collected with the D0 experiment. A novel calorimeter-based vectorial variable, "jet pull," is used, sensitive to the color-flow structure of the final state. We find that the fraction of uncolored W bosons is 0.56 +/- 0.42(stat + syst), in agreement with the standard model.
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| 44. |
- Abazov, V. M., et al.
(författare)
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Measurement of direct photon pair production cross sections 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. ; 690:2, s. 108-117
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Tidskriftsartikel (refereegranskat)abstract
- We present a measurement of direct photon pair production cross sections using 4.2 fb(-1) of data collected with the DO detector at the Fermilab Tevatron p (p) over bar Collider. We measure single differential cross sections as a function of the diphoton mass, the transverse momentum of the diphoton system, the azimuthal angle between the photons, and the polar scattering angle of the photons. In addition, we measure double differential cross sections considering the last three kinematic variables in three diphoton mass bins. The results are compared with different perturbative QCD predictions and event generators. (C) 2010 Elsevier B.V. All rights reserved.
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| 45. |
- Abazov, V. M., et al.
(författare)
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Measurement of sigma(p(p)over-bar -> Z plus X)Br(Z -> tau(+)tau(-)) at root s=1.96 TeV
- 2009
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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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| 46. |
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| 47. |
- Abazov, V. M., et al.
(författare)
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Measurement of Spin Correlation in t(t)over-bar Production Using a Matrix Element Approach
- 2011
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 107:3, s. 032001-
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Tidskriftsartikel (refereegranskat)abstract
- We determine the fraction of t (t) over bar events with spin correlation, assuming that the spin of the top quark is either correlated with the spin of the top antiquark as predicted by the standard model or is uncorrelated. For the first time we use a matrix-element-based approach to study t (t) over bar spin correlation. We use t (t) over bar -> W(+)bW(-)(b) over bar -> l(+)nu bl(-)(nu) over bar(b) over bar final states produced in p (p) over bar collisions at a center- of- mass energy root s = 1: 96 TeV, where l denotes an electron or a muon. The data correspond to an integrated luminosity of 5: 4 fb(-1) and were collected with the D0 detector at the Fermilab Tevatron collider. The result agrees with the standard model prediction. We exclude the hypothesis that the spins of the t (t) over bar are uncorrelated at the 97.7% C.L.
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| 48. |
- Abazov, V. M., et al.
(författare)
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Measurement of spin correlation in t(t)over-bar production using dilepton final states
- 2011
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 702:1, s. 16-23
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Tidskriftsartikel (refereegranskat)abstract
- We measure the correlation between the spin of the top quark and the spin of the anti-top quark in t (t) over bar -> W(+)bW(-)(b) over bar -> l(+)vbl(-) (v) over bar(b) over bar final states produced in p (p) over bar collisions at a center of mass energy root s = 1.96 TeV, where l is an electron or muon. The data correspond to an integrated luminosity of 5.4 fb(-1) and were collected with the D0 detector at the Fermilab Tevatron collider. The correlation is extracted from the angles of the two leptons in the t and (t) over bar rest frames, yielding a correlation strength C = 0.10(-0.45)(+0.45). in agreement with the NLO QCD prediction within two standard deviations, but also in agreement with the no correlation hypothesis.
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| 49. |
- Abazov, V. M., et al.
(författare)
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Measurement of t(t)over-bar production in the tau plus jets topology using p(p)over-bar collisions root s=1.96 TeV
- 2010
-
Ingår i: PHYS REV D. - 1550-7998. ; 82:7, s. 071102-
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Tidskriftsartikel (refereegranskat)abstract
- We present a measurement of the t (t) over bar production cross section multiplied by the branching ratio to tau lepton decaying semihadronically (tau(h)) plus jets, sigma(p (p) over bar -> t (t) over bar + X) center dot BR(t (t) over bar -> tau(h) + jets), at a center of mass energy root s = 1.96 TeV using 1 fb(-1) of integrated luminosity collected with the D0 detector. Assuming a top quark mass of 170 GeV, we measure sigma(t (t) over bar) center dot BR tau h (+ j) = 0.60(-0.22)(+0.23)(stat)(-0.14)(+0.15)(syst) +/- 0.04(lumi) pb. In addition, we extract the t (t) over bar production cross section using the t (t) over bar -> tau(h) + jets topology, with the result sigma(t (t) over bar) = 6.9(-1.2)(+1.2)(stat)(-0.7)(+0.8)(syst) +/- 0.4(lumi) pb. These findings are in good agreement with standard model predictions and measurements performed using other top quark decay channels.
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- Abazov, V. M., et al.
(författare)
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Measurement of the Angular and Lifetime Parameters of the Decays B-d(0) -> J/psi K*(0) and B-s(0) -> J/psi phi
- 2009
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:3, s. 032001-:102, s. 032001-
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Tidskriftsartikel (refereegranskat)abstract
- We present measurements of the linear polarization amplitudes and the strong relative phases that describe the flavor-untagged decays B-d(0) --> J/psi K*(0) and B-s(0) --> J/psi phi in the transversity basis. We also measure the mean lifetime (tau) over bar (s) of the B-s(0) mass eigenstates and the lifetime ratio (tau) over bar (s)/tau(d). The analyses are based on approximately 2.8 fb(-1) of data recorded with the D0 detector. From our measurements of the angular parameters we conclude that there is no evidence for a deviation from flavor SU( 3) symmetry for these decays and that the factorization assumption is not valid for the B-d(0) --> J/psi K*(0) decay.
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