Precise measurement of the $$t\bar{t}$$ production cross-section and lepton differential distributions in $$ e\mu $$ dilepton events from $$\sqrt{s}=13\,\text {TeV}$$ pp collisions with the ATLAS detector

UNSPECIFIED (2026) Precise measurement of the $$t\bar{t}$$ production cross-section and lepton differential distributions in $$ e\mu $$ dilepton events from $$\sqrt{s}=13\,\text {TeV}$$ pp collisions with the ATLAS detector. European Physical Journal C: Particles and Fields, 86 (5): 470. ISSN 1434-6044

Abstract

The inclusive top quark pair ( $$t\bar{t}$$ t t ¯ ) 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 $$140\,{\text {fb}^{-1}} $$ 140 fb - 1 of data collected by the ATLAS experiment at the Large Hadron Collider. Using events with an opposite-charge $$e\mu $$ e μ pair and b -tagged jets, the cross-section is measured to be: $$\begin{aligned} \sigma _{t\bar{t}} & = 829.3\pm 1.3\,\mathrm {(stat)}\ \pm 8.0\,\mathrm {(syst)}\ \pm 7.3\,\mathrm {(lumi)}\ \\ & \quad \pm 1.9\,\mathrm {(beam)}\,\textrm{pb}, \end{aligned}$$ σ t t ¯ = 829.3 ± 1.3 ( stat ) ± 8.0 ( syst ) ± 7.3 ( 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 proton beam energy, giving a total uncertainty of 1.3%. The result is used to determine the top quark pole mass via the dependence of the predicted cross-section on $${m_{t}^\textrm{pole}}$$ m t pole , giving $${m_{t}^\textrm{pole}}=172.8^{+1.5}_{-1.7}$$ m t pole = 172 . 8 - 1.7 + 1.5 $$\text {GeV}$$ GeV . The same event sample is used to measure absolute and normalised differential cross-sections for the $$t\bar{t} \rightarrow e\mu \nu \bar{\nu }b\bar{b} $$ t t ¯ → e μ ν ν ¯ b b ¯ process as a function of single-lepton and dilepton kinematic variables. Complementary measurements of $$e\mu b\bar{b} $$ e μ b b ¯ production, treating both $$t\bar{t}$$ t t ¯ and Wt events as signal, are also provided. Both sets of differential cross-sections are compared to the predictions of various Monte Carlo event generators, demonstrating that the state-of-the-art generators Powheg MiNNLO and Powheg bb 4 l describe the data better than Powheg .