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تسجيل مستخدم جديدRecent top quark production results from the Tevatron
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Oleg Brandt
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In this article, I review recent measurements of the production of the top quark in $pbar p$ collisions at a centre-of-mass energy of $sqrt s=1.96$~TeV in Run II of the Fermilab Tevatron Collider, recorded by the CDF and D0 Collaborations. I will present the Tevatron combination of measurements of the $tbar t$ production cross section and its differential measurement, the first evidence for and observation of the production of single top quarks in the $s$-channel, as well the final Tevatron combination of the production of single top quarks the $s$- and $t$-channels. Furthermore, I will review the measurements of the forward-backward asymmetry in $tbar t$ events, which can be experimentally uniquely accessed in the $CP$-invariant $pbar p$ initial state at the Tevatron, and conclude with the measurements of this asymmetry in the $bbar b$ system.
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This report describes latest measurements and studies of top quark properties from the Tevatron in RunII with an integrated luminosity of up to 750pb-1. Due to its large mass of about 172GeV, the top quark provides a unique environment for tests of t
he Standard Model and is believed to yield sensitivity to new physics beyond the Standard Model. With data samples of close to 1fb-1 the CDF and D0 collaborations at the Tevatron enter a new aera of precision top quark measurements.
This paper reports on the first observation of electroweak production of single top quarks by the DZero and CDF collaborations. At Fermilabs 1.96 TeV proton-antiproton collider, a few thousand events are selected from several inverse femtobarns of da
ta that contain an isolated electron or muon and/or missing transverse energy, together with jets that originate from the decays of b quarks. Using sophisticated multivariate analyses to separate signal from background, the DZero collaboration measures a cross section sigma(ppbar->tb+X,tqb+X) = 3.94 +- 0.88 pb (for a top quark mass of 170 GeV) and the CDF collaboration measures a value of 2.3_0.6 -0.5 pb (for a top quark mass of 175 GeV). These values are consistent with theoretical predictions at next-to-leading order precision. Both measurements have a significance of 5.0 standard deviations, meeting the benchmark to be considered unambiguous observation.
The production of single-top quarks occurs via the weak interaction at the Fermilab Tevatron proton-antiproton collider. Single top quark events are selected in the lepton+jets final state by CDF and D0 and in the missing transverse energy plus jets
final state by CDF. Multivariate classifiers separate the s-channel and t-channel single-top signals from the large backgrounds. The combination of CDF and D0 results leads to the first observation of the s-channel mode of single top quark production. The t-channel and single top combined cross sections have also been measured.
The top quark, discovered in 1995 by the CDF and D0 collaborations at the Tevatron proton antiproton collider at Fermilab, has undergone intense studies in the last 20 years. Currently, CDF and D0 converge on their measurements of top-antitop quark p
roduction cross sections using the full Tevatron data sample. In these proceedings, the latest results on inclusive and differential measurements of top-antitop quark production cross sections at the Tevatron are reported.
The CDF and D0 experiments at the Tevatron ppbar collider have pioneered and established the role of flavor physics in hadron collisions. A broad program is now at its full maturity. We report on three new results sensitive to physics beyond the stan
dard model, obtained using the whole CDF dataset: a measurement of the difference of CP asymmetries in $K^+K^-$ and $pi^+pi^-$ decays of $D^0$ mesons, new bounds on the $B^0_s$ mixing phase and on the decay width difference of $B^0_s$ mass-eigenstates, and an update of the summer 2011 search for $B^0_(s)$ mesons decaying into pairs of muons. Finally, the D0 confirmation of the observation of a new hadron, the $chi_b(3P)$ state, is briefly mentioned.
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