A measurement of the top quark pair-production cross section in the $\mathrm{lepton}+\text{jets}$ decay channel is presented. It is based on $4.6{\mathrm{fb}}^{-1}$ of $\sqrt{s}=7\mathrm{TeV}$ $pp$ collision data collected during 2011 by the ATLAS experiment at the CERN Large Hadron Collider. A three-class, multidimensional event classifier based on support vector machines is used to differentiate $t\overline{t}$ events from backgrounds. The $t\overline{t}$ production cross section is found to be ${\sigma }_{t\overline{t}}=168.5\pm 0.7(\mathrm{stat}){}_{-5.9}^{+6.2}(\mathrm{syst}){}_{-3.2}^{+3.4}(\mathrm{lumi})\mathrm{pb}$. The result is consistent with the Standard Model prediction based on QCD calculations at next-to-next-to-leading order.

• Received 2 December 2022
• Accepted 14 March 2023

DOI:https://doi.org/10.1103/PhysRevD.108.032014

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