Here, we summarize the ongoing scientific program of the 12 GeV Continuous Electron Beam Accelerator Facility (CEBAF) and give an outlook into future opportunities. The program addresses important ...topics in nuclear, hadronic, and electroweak physics, including nuclear femtography, meson and baryon spectroscopy, quarks and gluons in nuclei, precision tests of the standard model and dark sector searches. Potential upgrades of CEBAF and their impact on scientific reach are discussed, such as higher luminosity, the addition of polarized and unpolarized positron beams, and doubling the beam energy.
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 σt=2.25+0.29−0.31 pb. We also present the combinations of the two-dimensional measurements of the s- vs. t-channel cross sections and of the s+t channel cross section measurement resulting in σs+t=3.30+0.52−0.40 pb, without assuming the standard-model value for the ratio σs/σt. The resulting value of the magnitude of the top-to-bottom quark coupling is |Vtb| = 1.02+0.06−0.05, corresponding to |Vtb|>0.92 at the 95% C.L.
We report a search for the standard model Higgs boson in the missing energy and acoplanar b-jet topology, using an integrated luminosity of 0.93 fb;{-1} recorded by the D0 detector at the Fermilab ...Tevatron ppover Collider. The analysis includes signal contributions from ppover -->ZH-->nunuover bbover , as well as from WH production in which the charged lepton from the W boson decay is undetected. Neural networks are used to separate signal from background. In the absence of a signal, we set limits on sigma(ppover -->VH)xB(H-->bbover ) at the 95% C.L. of 2.6-2.3 pb, for Higgs boson masses in the range 105-135 GeV, where V=W, Z. The corresponding expected limits range from 2.8 to 2.0 pb.
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.
We describe a measurement of the mass of the top quark from the purely hadronic decay modes of tt¯ pairs using all-jet data produced in pp¯ collisions at s=1.8 TeV at the Fermilab Tevatron Collider. ...The data, which correspond to an integrated luminosity of 110.2±5.8 pb−1, were collected with the DØ detector from 1992 to 1996. We find a top quark mass of 178.5±13.7(stat)±7.7(syst) GeV/c2.
The upgraded DØ detector Abazov, V.M.; Alves, G.A.; Askew, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2006, Letnik:
565, Številka:
2
Journal Article
Recenzirano
The DØ 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 I, are discussed briefly. We also present the associated electronics, triggering, and data acquisition systems, along with the design and implementation of software specific to DØ.
We present results from a study of pp-->Wgamma+X events utilizing data corresponding to 0.7 fb{-1} of integrated luminosity at sqrts=1.96 TeV collected by the D0 detector at the Fermilab Tevatron ...Collider. We set limits on anomalous WWgamma couplings at the 95% C.L. The one-dimensional 95% C.L. limits are 0.49<kappa{gamma}<1.51 and -0.12<lambda{gamma}<0.13. We make the first study of the charge-signed rapidity difference between the lepton and the photon and find it to be indicative of the standard model radiation-amplitude zero in the Wgamma system.
We present evidence for the exotic charged charmoniumlike state Z(c)(+/-)(3900) decaying to J/psi pi(+/-) in semi-inclusive weak decays of b-flavored hadrons. The signal is correlated with a parent ...J/psi pi(+)pi(-) system in the invariant-mass range 4.2-4.7 GeV that would include the exotic structure Y(4260). The study is based on 10.4 fb(-1) of p (p) over bar collision data collected by the D0 experiment at the Fermilab Tevatron collider.
Here, the inclusive cross section of top quark-antiquark pairs produced in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV is measured in the lepton+jets and dilepton decay channels. The data sample ...corresponds to 9.7 fb-1 of integrated luminosity recorded with the D0 detector during Run II of the Fermilab Tevatron Collider. Employing multivariate analysis techniques we measure the cross section in the two decay channels and we perform a combined cross section measurement. For a top quark mass of 172.5 GeV, we measure a combined inclusive top quark-antiquark pair production cross section of σ$t\bar{t}$=7.26±0.13(stat)$+0.57\atop{-0.50}$(syst) pb which is consistent with standard model predictions. We also perform a likelihood fit to the measured and predicted top quark mass dependence of the inclusive cross section, which yields a measurement of the pole mass of the top quark. The extracted value is mt=172.8±1.1(theo)$+3.3\atop{-3.1}$(exp) GeV.
We report evidence for the simultaneous production of J/ψ and ϒ mesons in 8.1 fb^{-1} of data collected at sqrts=1.96 TeV by the D0 experiment at the Fermilab ppover ¯ Tevatron Collider. Events ...with these characteristics are expected to be produced predominantly by gluon-gluon interactions. In this analysis, we extract the effective cross section characterizing the initial parton spatial distribution, σ_{eff}=2.2±0.7(stat)±0.9(syst) mb.
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