/ hep-ex CERN-EP-2017-276

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

Pages: 49

Abstract: The inclusive and fiducial $t\bar{t}$ production cross-sections are 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 on 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 $\sigma_{\text{inc}}(t\bar{t})$ = 248.3 $\pm$ 0.7 (stat.) $\pm$ 12.8 (syst.) $\pm$ 4.7 (lumi.) pb, assuming a top-quark mass of 172.5 GeV. The result is in agreement with the Standard Model prediction. The cross-section is also measured in a phase space close to that of the selected data. The fiducial cross-section is $\sigma_{\text{fid}}(t\bar{t})$ = 48.8 $\pm$ 0.1 (stat.) $\pm$ 2.0 (syst.) $\pm$ 0.9 (lumi.) pb with a precision of 4.5%.

Note: *Temporary entry*; 49 pages in total, author list starting page 32, 7 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/TOPQ-2016-08/

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Запись создана 2018-01-09, последняя модификация 2018-01-09

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