Measurement of the tt¯ cross section and its ratio to the Z production cross section using pp collisions at s=13.6 TeV with the ATLAS detector

The ATLAS collaboration
Phys.Lett.B 848 (2024) 138376, 2024.

Abstract
The inclusive top-quark-pair production cross section σtt¯ and its ratio to the Z-boson production cross section have been measured in proton--proton collisions at s=13.6 TeV, using 29 fb1 of data collected in 2022 with the ATLAS experiment at the Large Hadron Collider. Using events with an opposite-charge electron-muon pair and b-tagged jets, and assuming Standard Model decays, the top-quark-pair production cross section is measured to be σtt¯=850±3(stat.)±18(syst.)±20(lumi.) pb. The ratio of the tt¯ and the Z-boson production cross sections is also measured, where the Z-boson contribution is determined for inclusive e+e and μ+μ events in a fiducial phase space. The relative uncertainty on the ratio is reduced compared to the tt¯ cross section, thanks to the cancellation of several systematic uncertainties. The result for the ratio, Rtt¯/Z=1.145±0.003(stat.)±0.021(syst.)±0.002(lumi.) is consistent with the Standard Model prediction using the PDF4LHC21 PDF set.

  • Z-boson phase-space

    10.17182/hepdata.143515.v1/t1

    The fiducial phase-space definition for the Z-boson measurement. Born-level leptons are used.

  • Cross section and ratio results

    10.17182/hepdata.143515.v1/t2

    The measured tt¯ cross section and the ratio of the cross sections of tt¯ and the Z-boson. Full phase-space is...

  • Pre-fit yields

    Data from Figure 2 (left)

    10.17182/hepdata.143515.v1/t3

    Table with pre-fit yields in the four regions used in the measurement

  • Post-fit yields

    Data from Figure 2 (right)

    10.17182/hepdata.143515.v1/t4

    Table with post-fit yields in the four regions used in the measurement. The correlations of the nuisance parameters, as obtained...

  • Cross section ratio theory comparison

    Data from Figure 4

    10.17182/hepdata.143515.v1/t5

    Ratio of the tt¯ to the Z-boson cross section compared to the predictions for several sets of parton distribution functions....

  • tt¯ cross section nuisance parameter ranking

    Data from Figure 5 of the Auxiliary material

    10.17182/hepdata.143515.v1/t6

    Nuisance parameter ranking plot for the tt¯ signal-strength. Only the 10 most important nuisance parameters are shown. The impact of...

  • Cross section ratio nuisance parameter ranking

    Data from Figure 6 of the Auxiliary material

    10.17182/hepdata.143515.v1/t7

    Nuisance parameter ranking plot for the ratio of the tt¯ and Z-boson signal-strengths. Only the 10 most important nuisance parameters...

  • Z-boson cross section nuisance parameter ranking

    Data from Figure 7 of the Auxiliary material

    10.17182/hepdata.143515.v1/t8

    Nuisance parameter ranking plot for the Z-boson signal-strength. Only the 10 most important nuisance parameters are shown. The impact of...

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