Top Physics

The current status of the measurements of the top-antitop (t¯t)
differential cross section with respect to the t¯t system transverse momentum (pT ) is presented. The used data sample of 4.7 fb−1 is recorded with the ATLAS detector at the Large Hadron Collider

This talk is an overview of recent results on top-quark physics obtained by the ATLAS collaboration from the analysis of $pp$ collisions at $\sqrt{s} = $ 7 and 8 TeV at the Large Hadron Collider. Total and differential top-quark pair cross-section, single top cross-section and mass measurements are presented.

Recent results of searches for new physics in top events at the Tevatron are presented. In case of CDF three searches are discussed using 6.0 to 8.7 fb^{-1} of data, with the latter being the final CDF data sample available for this kind of analysis. CDF carried out a search for Top + jet resonance production, dark matter production in association with single top and boosted tops. No signs of new physics are observed and instead upper limits are derived. D{\O} used 5.3 fb^{-1} of data and searched for a narrow resonance in ttbar production and a time dependent ttbar cross section, which would reveal a violation of Lorentz invariance. However, no signs for deviations from Standard Model are seen and instead upper limits for non-Standard Model contributions are calculated.

Differential cross sections in the top quark sector measured at the Fermilab Tevatron collider are presented. CDF used 2.7 fb$^{-1}$ of data and measured the differential cross section as a function of the invariant mass of the $t\bar{t}$ system. The measurement shows good agreement with the standard model and furthermore is used to derive limits on the ratio $\kappa /M_{Pl}$ for gravitons which decay to top quarks in the Randall-Sundrum model. D0 used 1.0 fb$^{-1} of data to measure the differential cross section as a function of the transverse momentum of the top quark. The measurement shows a good agreement to the higher order perturbative QCD prediction and various predictions based on various Monte-Carlo generators.

Four measurements of $t\bar{t}$ differential cross section at $\sqrt{s}=7~\tev$ will be presented: respect to the transverse momentum, the mass and the rapidity of the $t\bar{t}$ system and to the transverse momentum of the individual top.
% \red{(mettere in risalto che il pt \`e la prima misura di questo tipo in atlas?}.

The analysis was carried over a data sample of $4.7\,\mathrm{fb}^{-1}$ recorded by the ATLAS detector, selecting events in the lepton+jets channel using a cut based approach.

The final background subtracted distributions were corrected for detector and selection effects using unfolding methods. The measurements are dominated by the systematic uncertainties and show good agreement with the Standard Model predictions.