Inclusive and differential cross-section measurements of ttZ¯ production in pp collisions at √s = 13 TeV with the ATLAS detector, including EFT and spin-correlation interpretations
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Date
2024
Authors
Aad, G.
Abbott, B.
Abeling, K.
Abicht, N.J.
Abidi, S.H.
Aboulhorma, A.
Abramowicz, H.
Abreu, H.
Abulaiti, Y.
Acharya, B.S.
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Journal article
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Journal of High Energy Physics (JHEP), 2024; 2024(7):163-1-163-108
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The ATLAS collaboration
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Abstract
Measurements of both the inclusive and diferential production cross sections of a top-quark-top-antiquark pair in association with a Z boson (ttZ¯ ) are presented. Final states with two, three or four isolated leptons (electrons or muons) are targeted. The measurements use the data recorded by the ATLAS detector in pp collisions at √ s = 13 TeV at the Large Hadron Collider during the years 2015–2018, corresponding to an integrated luminosity of 140 fb−1 . The inclusive cross section is measured to be σttZ¯ = 0.86±0.04 (stat.)±0.04 (syst.) pb and found to be in agreement with the most advanced Standard Model predictions. The diferential measurements are presented as a function of a number of observables that probe the kinematics of the ttZ¯ system. Both the absolute and normalised diferential cross-section measurements are performed at particle level and parton level for specifc fducial volumes, and are compared with NLO+NNLL theoretical predictions. The results are interpreted in the framework of Standard Model efective feld theory and used to set limits on a large number of dimension-6 operators involving the top quark. The frst measurement of spin correlations in ttZ¯ events is presented: the results are in agreement with the Standard Model expectations, and the null hypothesis of no spin correlations is disfavoured with a signifcance of 1.8 standard deviations.
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© CERN 2024, for the benefit of the ATLAS Collaboration. Article funded by SCOAP3. Open Access . This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.