Measurement of high-mass $$t\bar{t}\ell ^{+}\ell ^{-}$$ production and lepton flavour universality-inspired effective field theory interpretations at $$\sqrt{s}=13$$ $$\text {T}\text {e}\hspace{-1.00006pt}\text {V}$$ with the ATLAS detector

Ali, Hanadi and Alsolami, Zainab and Barton, A.E. and Borissov, G. and Bouhova-Thacker, E.V. and Fernandez Barbadillo, B. and Ferrando, James and Fox, H. and Hagan, Alina and Jones, R.W.L. and Kartvelishvili, V. and Love, P.A. and Marshall, Emma J. and McElhinney, Luke and Meng, L. and Sampson, Elliot and Smizanska, M. and Wharton, A.M. (2025) Measurement of high-mass $$t\bar{t}\ell ^{+}\ell ^{-}$$ production and lepton flavour universality-inspired effective field theory interpretations at $$\sqrt{s}=13$$ $$\text {T}\text {e}\hspace{-1.00006pt}\text {V}$$ with the ATLAS detector. European Physical Journal C: Particles and Fields, 85 (12): 1434. ISSN 1434-6044

Abstract

Measurements of $$t\bar{t}\ell ^{+}\ell ^{-}$$ t t ¯ ℓ + ℓ - production in the region of high dilepton invariant mass with effective field theory (EFT) interpretations are presented. They are performed using final states with three isolated leptons (electrons or muons) and are based on $$\sqrt{s} = 13$$ s = 13 $$\text {T}\text {e}\hspace{-1.00006pt}\text {V}$$ Te V proton–proton collision data with an integrated luminosity of $$140\,\textrm{fb}^{-1}$$ 140 fb - 1 , recorded from 2015 to 2018 with the ATLAS detector at the Large Hadron Collider. Measurements of the $$t\bar{t}\,\ell ^+\ell ^-$$ t t ¯ ℓ + ℓ - signal strength and cross-section upper-limits are performed inclusively in lepton flavour and separately for electrons and muons. The study also aims to probe anomalous four-fermion interactions including to test for possible lepton flavor universality violation. No significant deviations from the Standard Model predictions are observed and the measurements are interpreted through the EFT formalism to provide new constraints on the relevant operators.