Abstract
Measurements of the inclusive and differential cross-sections for top-quark pair and single top production cross sections in proton-proton collisions with the ATLAS detector at the Large Hadron Collider are presented at centre-of-mass energies of 8 TeV and 13 TeV.The inclusive measurements reach high precision and are compared to the best available theoretical calculations. These measurements, including results using boosted tops, probe our understanding of top-pair production in the TeV regime. The results are compared to Monte Carlo generators implementing LO and NLO matrix elements matched with parton showers and NLO QCD calculations.For the t-channel single top measurement, the single top-quark and anti-top-quark total production cross-sections, their ratio, as well as differential cross sections are also presented. A measurement of the production cross section of a single top quark in association with a W boson, the second largest single-top production mode, is also presented. Finally, measurements of the properties of the Wtb vertex allow to set limits on anomalous couplings. All measurements are compared to state-of-the-art theoretical calculations.
Highlights
Measurements of the inclusive and differential cross-sections for top-quark pair and single top production cross sections in proton-proton collisions with the ATLAS detector at the Large Hadron Collider are presented at centre-ofmass energies of 8 TeV and 13 TeV
Almost every top quark decays into a W boson and a b quark pair, and it is possible to have three different ttfinal states, depending on the decay of the Ws in a lepton-neutrino or a quark-antiquark pair: the hadronic channel, the lepton+jets channel and the di-lepton channel
The measurement is performed through a Boosted Decision Tree, in order to separate the Wt signal from the ttbackground obtaining discriminant variables which are used in a profile likelihood fit to calculate the Wt cross section
Summary
The top quark, discovered in 1995 by both the CDF [1] and D0 [2] collaborations at the Tevatron collider, is the heaviest known particle of the Standard Model. Almost every top quark decays into a W boson and a b quark pair, and it is possible to have three different ttfinal states, depending on the decay of the Ws in a lepton-neutrino or a quark-antiquark pair: the hadronic channel, the lepton+jets channel and the di-lepton channel In this overview some of the most recent measurements of top pair and single top production cross section, obtained by the ATLAS Collaboration using data collected in 2012 For higher momentum top quarks, their decay products tend to become more collimated, making the previous reconstruction techniques less efficient In this case, usually known as boosted topology, the events are selected looking for one charged lepton, at least one jet, a certain amount of missing transverse energy and the hadronically decaying top quark is reconstructed as a single large radius jet.
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