In these proceedings, I review recent measurements in the top quark sector in pp-bar collisions at a centre-of-mass energy of √s = 1.96 TeV in Run II of the Fermilab Tevatron Collider using the D0 detector. I will present the differential measurement of the tt-bar production cross section and the Tevatron combination of inclusive tt-bar cross section measurements; the first evidence of the production of single top quarks in the s-channel by D0 and the observation in combination with CDF. Furthermore, I will review the measurements of the forward-backward asymmetry in tt-bar events, and conclude with the world's most precise single measurement of the top quark mass, which is a fundamental parameter of the standard model, and present the Tevatron combination, which is the world's most precise determination of the top quark mass, with a relative precision of 0.37%.

I present recent results on top quark production in pp collisions at a center of mass energy of 1.96 TeV. The studies were performed by the D0 collaboration using approximately 5 fb−1 of data taken during Run II at the Fermilab Tevatron accelerator. The top quark is the heaviest known elementary particle and completes the quark sector of the three-generation structure of the standard model (SM). It differs from the other quarks not only by its much larger mass, but also by its lifetime which is too short to build hadronic bound states. The SM predicts that top quarks are created via two independent production mechanisms at hadron colliders. The primary mode, in which a t{bar t} pair is produced from a gtt vertex via the strong interaction, was used by the D0 and CDF collaborations to establish the existence of the top quark in 1995. The second production mode of top quarks at hadron colliders is the electroweak production of a single top quark from a Wtb vertex. The predicted cross section for single top quark production is about half that of t{bar t} pairs but the signal-to-background ratio is much worse; observation of single top quark production has therefore until recently been impeded by its low rate and difficult background environment compared to the top pair production. In the following sections I will present results for the measurement of the t{bar t} pair and the single top quark production cross section using respectively 5.3 fb−1 and 5.4 fb−1 of data taken by the D0 experiment.

Recent results on top quark physics with the D0 experiment in {anti p}p collisions at √s = 1.8 TeV for an integrated luminosity of 125 pb−1 are reported. The direct measurement of the top quark mass uses single lepton events, giving the result m{sub top} = 173.3 ± 5.6(stat) ± 6.2(syst) GeV=c2. The measurement of the t{anti t} production cross section includes analyses from 8 top decay channels: dilepton (t{anti t} → e[mu], ee, and [mu][mu]), electron and neutrino (t{anti t} → e[nu]), and single leptons (t{anti t} → e + jets and t{anti t} → [mu] + jets) with and without b tagging. We measure the t{anti t} production cross section to be 5.5 ± 1.8 pb at m{sub top} = 173.3 GeV/c2.

We present the most recent measurements on top-quark physics obtained with Tevatron $p\bar{p}$ collisions recorded by the D0 experiment at $\sqrt{s}= 1.96$ TeV. The full Run II data set of 9.7 fb$^{-1}$ is analyzed. Both lepton+jets and dilepton channels of top-quark pair production are used to measure the differential and inclusive cross sections, the forward-backward asymmetries, the top-quark mass, the spin correlations, and the top-quark polarization.

The top quark is by far the heaviest known fundamental particle with a mass nearing that of a gold atom. Because of this strikingly high mass, the top quark has several unique properties and might play an important role in electroweak symmetry breaking—the mechanism that gives all elementary particles mass. Creating top quarks requires access to very high energy collisions, and at present only the Tevatron collider at Fermilab is capable of reaching these energies. Until now, top quarks have only been observed produced in pairs via the strong interaction. At hadron colliders, it should also be possible to produce single top quarks via the electroweak interaction. Studies of single top quark production provide opportunities to measure the top quark spin, how top quarks mix with other quarks, and to look for new physics beyond the standard model. Because of these interesting properties, scientists have been looking for single top quarks for more than 15 years. This thesis presents the first discovery of single top quark production. It documents one of the flagship measurements of the D0 experiment, a collaboration of more than 600 physicists from around the world. It describes first observation of a physical process known as “single top quark production”, which had been sought for more than 10 years before its eventual discovery in 2009. Further, his thesis describes, in detail, the innovative approach Dr. Gillberg took to this analysis. Through the use of Boosted Decision Trees, a machine-learning technique, he observed the tiny single top signal within an otherwise overwhelming background. This Doctoral Thesis has been accepted by Simon Fraser University, Burnaby, BC, Canada.

Recent results on top quark physics with the D0 experiment in pp collisions at (square root)s = 1.8 TeV are reported. The direct measurement of the top quark mass uses single lepton and dilepton events, giving the result m{sub top} = 172.1 " 7.1 GeV/c2 . The measurement of the t{anti t} production cross section includes analyses from 9 top decay channels: dilepton, electron and neutrino, single leptons with and without b tagging, and all-jets (t{anti t} --> b jets). The authors measured the t{anti t} production cross section to be 5.9 " 1.7 pb at m{sub top} = 172.1 GeV/c2. Preliminary results on a search for charged Higgs production in top events are presented.

In this talk I will present recent preliminary results from the D0 experiment from Tevatron Run II (p{bar p} collisions at {radical}s = 1.96 TeV). The results presented in this talk include top quark pair production cross section, top quark mass, and upper limits on single top quark production.