Measurements of both the inclusive and differential production cross sections of a top-quark-top-antiquark pair in association with a Z boson (tt¯Z) 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 σtt¯Z = 0.86 ± 0.04 (stat.) ± 0.04 (syst.) pb and found to be in agreement with the most advanced Standard Model predictions. The differential measurements are presented as a function of a number of observables that probe the kinematics of the tt¯Z system. Both the absolute and normalised differential cross-section measurements are performed at particle level and parton level for specific fiducial volumes, and are compared with NLO+NNLL theoretical predictions. The results are interpreted in the framework of Standard Model effective field theory and used to set limits on a large number of dimension-6 operators involving the top quark. The first measurement of spin correlations in tt¯Z 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 significance of 1.8 standard deviations.

Null, N., Aad, G., Abbott, B., Abeling, K., Abicht, N.J., Abidi, S.H., et al. (2024). Inclusive and differential cross-section measurements of $$ t\overline{t}Z $$ production in pp collisions at $$ \sqrt{s} $$ = 13 TeV with the ATLAS detector, including EFT and spin-correlation interpretations. JOURNAL OF HIGH ENERGY PHYSICS, 2024(7), 163-1-163-108 [10.1007/jhep07(2024)163].

Inclusive and differential cross-section measurements of $$ t\overline{t}Z $$ production in pp collisions at $$ \sqrt{s} $$ = 13 TeV with the ATLAS detector, including EFT and spin-correlation interpretations

Alberghi, G. L.;Alfonsi, F.;Ballabene, E.;Bellagamba, L.;Bianco, G.;Boscherini, D.;Bruni, A.;Carratta, G.;Cremonini, D.;De Castro, S.;Fabbri, F.;Fabbri, L.;Franchini, M.;Gabrielli, A.;Giacobbe, B.;Lasagni Manghi, F.;Polini, A.;Rinaldi, L.;Romano, M.;Sbarra, C.;Sbrizzi, A.;Semprini-Cesari, N.;Sioli, M.;Todome, K.;Valentinetti, S.;Villa, M.;Vittori, C.;Vivarelli, I.;Zoccoli, A.;
2024

Abstract

Measurements of both the inclusive and differential production cross sections of a top-quark-top-antiquark pair in association with a Z boson (tt¯Z) 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 σtt¯Z = 0.86 ± 0.04 (stat.) ± 0.04 (syst.) pb and found to be in agreement with the most advanced Standard Model predictions. The differential measurements are presented as a function of a number of observables that probe the kinematics of the tt¯Z system. Both the absolute and normalised differential cross-section measurements are performed at particle level and parton level for specific fiducial volumes, and are compared with NLO+NNLL theoretical predictions. The results are interpreted in the framework of Standard Model effective field theory and used to set limits on a large number of dimension-6 operators involving the top quark. The first measurement of spin correlations in tt¯Z 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 significance of 1.8 standard deviations.
2024
Null, N., Aad, G., Abbott, B., Abeling, K., Abicht, N.J., Abidi, S.H., et al. (2024). Inclusive and differential cross-section measurements of $$ t\overline{t}Z $$ production in pp collisions at $$ \sqrt{s} $$ = 13 TeV with the ATLAS detector, including EFT and spin-correlation interpretations. JOURNAL OF HIGH ENERGY PHYSICS, 2024(7), 163-1-163-108 [10.1007/jhep07(2024)163].
Null, Null; Aad, G.; Abbott, B.; Abeling, K.; Abicht, N. J.; Abidi, S. H.; Aboulhorma, A.; Abramowicz, H.; Abreu, H.; Abulaiti, Y.; Acharya, B. S.; Ad...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/1007302
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