Measurement of the inclusive $t\bar{t}$ cross-section in the lepton+jets channel in $pp$ collisions at $\sqrt{s}$ = 8 TeV with the ATLAS detector

The inclusive $t\bar{t}$ production cross-section is measured in the lepton+jets channel using 20.2 fb${}^{-1}$ of proton–proton collision data at a centre-of-mass energy of 8 TeV recorded with the ATLAS detector at the LHC. Major systematic uncertainties due to the modelling of the jet energy scale and $b$-tagging efficiency are constrained by separating selected events into three disjoint regions. In order to reduce systematic uncertainties in the most important background, the W+jets process is modelled using Z+jets events in a data-based approach. The inclusive $t\bar{t}$ cross-section is measured with a precision of 5.7% to be $\sigma_{t\bar{t}} = 248.3 \pm 0.7 , ($\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}\mathrm{.}$) \pm 13.4 , ($\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{.}$) \pm 4.7 , ($\mathrm{l}\mathrm{u}\mathrm{m}\mathrm{i}\mathrm{.}$)~$\text{pb}$$, assuming a top-quark mass of 172.5 GeV. The result is in agreement with the Standard Model prediction.