297 research outputs found
Combined Forward-Backward Asymmetry Measurements in Top-Antitop Quark Production at the Tevatron
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 TeV. We report the results of combinations of the inclusive asymmetries and their differential dependencies on relevant kinematic quantities. The combined inclusive asymmetry is . The combined inclusive and differential asymmetries are consistent with recent standard model predictions
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Inclusive jet production at 630 and 1800 GeV
Inclusive jet cross sections measured at the Fermilab Tevatron p{anti p} Collider are presented and compared to theoretical predictions. The cross sections are reported as a function of jet E{sub T} at beam energies of {radical}s = 0.63 TeV and {radical}s = 1.8 TeV. A recent preliminary result at {radical}s = 1.8 TeV by the CDF collaboration confirms an earlier published result which is in good agreement with Quantum Chromodynamics (QCD) below E{sub T} = 250 GeV, but which shows excess jet production above 250 GeV. A final result by the D0 collaboration is in good agreement with QCD at all E{sub T} . An uncertainty analysis, including a final D0 systematic error matrix, indicates the two measurements are consistent. Preliminary {radical}s = 0.63 TeV cross sections from the two experiments are consistent with one another but somewhat lower than QCD predictions. Likewise, preliminary measurements of the ratio of cross sections at {radical}s = 0.63 TeV and {radical}s = 1.8 TeV are experimentally consistent, but approximately 20% below predictions
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Run II jet physics: Proceedings of the Run II QCD and weak boson physics workshop
The Run II jet physics group includes the Jet Algorithms, Jet Shape/Energy Flow, and Jet Measurements/Correlations subgroups. The main goal of the jet algorithm subgroup was to explore and define standard Run II jet finding procedures for CDF and D0. The focus of the jet shape/energy flow group was the study of jets as objects and the energy flows around these objects. The jet measurements/correlations subgroup discussed measurements at different beam energies; {alpha}{sub S} measurements; and LO, NLO, NNLO, and threshold jet calculations. As a practical matter the algorithm and shape/energy flow groups merged to concentrate on the development of Run II jet algorithms that are both free of theoretical and experimental difficulties and able to reproduce Run I measurements. Starting from a review of the experience gained during Run I, the group considered a variety of cone algorithms, and K{sub T} algorithms. The current understanding of both types of algorithms, including calibration issues, are discussed in this report along with some preliminary experimental results. The jet algorithms group recommends that CDF and D0 employ the same version of both a cone algorithm and a K{sub T} algorithm during Run II. Proposed versions of each type of algorithm are discussed. The group also recommends the use of full 4-vector kinematic variables whenever possible. The recommended algorithms attempt to minimize the impact of seeds in the case of the cone algorithm and preclustering in the case of the K{sub T} algorithm. Issues regarding precluster definitions and merge/split criteria require further study
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