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AbstractThe inclusive top quark pair ($$t\bar{t}$$ t t ¯ ) production cross-section $$\sigma _{t\bar{t}}$$ σ t t ¯ has been measured in proton–proton collisions at $$\sqrt{s}=13\,\text {TeV}$$ s = 13 TeV , using 36.1 fb$$^{-1}$$ - 1 of data collected in 2015–2016 by the ATLAS experiment at the LHC. Using events with an opposite-charge $$e\mu $$ e μ pair and b-tagged jets, the cross-section is measured to be: $$\begin{aligned} \sigma _{t\bar{t}} = 826.4 \pm 3.6\,\mathrm {(stat)}\ \pm 11.5\,\mathrm {(syst)}\ \pm 15.7\,\mathrm {(lumi)}\ \pm 1.9\,\mathrm {(beam)}\,\mathrm {pb}, \end{aligned}$$ σ t t ¯ = 826.4 ± 3.6 ( stat ) ± 11.5 ( syst ) ± 15.7 ( lumi ) ± 1.9 ( beam ) pb , where the uncertainties reflect the limited size of the data sample, experimental and theoretical systematic effects, the integrated luminosity, and the LHC beam energy, giving a total uncertainty of 2.4%. The result is consistent with theoretical QCD calculations at next-to-next-to-leading order. It is used to determine the top quark pole mass via the dependence of the predicted cross-section on $$m_t^{\mathrm{pole}}$$ m t pole , giving $$m_t^{\mathrm{pole}}=173.1^{+2.0}_{-2.1}\,\text {GeV}$$ m t pole = 173 . 1 - 2.1 + 2.0 GeV . It is also combined with measurements at $$\sqrt{s}=7\,\text {TeV}$$ s = 7 TeV and $$\sqrt{s}=8\,\text {TeV}$$ s = 8 TeV to derive ratios and double ratios of $$t\bar{t}$$ t t ¯ and Z cross-sections at different energies. The same event sample is used to measure absolute and normalised differential cross-sections as functions of single-lepton and dilepton kinematic variables, and the results are compared with predictions from various Monte Carlo event generators.