%0 Journal Article %T Measurement of the t(t)over-bart(t)over-bar production cross section in pp collisions at root s=13 TeV with the ATLAS detector %A ATLAS Collaboration (Aad, G. et al %A Aparisi Pozo, J. A. %A Bailey, A. J. %A Cabrera Urban, S. %A Cardillo, F. %A Castillo, F. L. %A Castillo Gimenez, V. %A Costa, M. J. %A Didenko, M. %A Escobar, C. %A Estrada Pastor, O. %A Ferrer, A. %A Fiorini, L. %A Fullana Torregrosa, E. %A Fuster, J. %A Garcia, C. %A Garcia Navarro, J. E. %A Gonzalez de la Hoz, S. %A Gonzalvo Rodriguez, G. R. %A Guerrero Rojas, J. G. R. %A Higon-Rodriguez, E. %A Lacasta, C. %A Lozano Bahilo, J. J. %A Mamuzic, J. %A Marti-Garcia, S. %A Martinez Agullo, P. %A Miralles Lopez, M. %A Mitsou, V. A. %A Moreno Llacer, M. %A Navarro-Gonzalez, J. %A Poveda, J. %A Prades IbaƱez, A. %A Ruiz-Martinez, A. %A Sabatini, P. %A Salt, J. %A Sanchez Sebastian, V. %A Sayago Galvan, I. %A Soldevila, U. %A Sanchez, J. %A Torro Pastor, E. %A Valero, A. %A Valls Ferrer, J. A. %A Villaplana Perez, M. %A Vos, M. %J Journal of High Energy Physics %D 2021 %V 11 %N 11 %I Springer %@ 1029-8479 %G English %F ATLASCollaborationAad_etal2021 %O WOS:000722987000001 %O exported from refbase (https://references.ific.uv.es/refbase/show.php?record=5030), last updated on Tue, 07 Dec 2021 11:47:48 +0000 %X A measurement of four-top-quark production using proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the ATLAS detector at the Large Hadron Collider corresponding to an integrated luminosity of 139 fb(-1) is presented. Events are selected if they contain a single lepton (electron or muon) or an opposite-sign lepton pair, in association with multiple jets. The events are categorised according to the number of jets and how likely these are to contain b-hadrons. A multivariate technique is then used to discriminate between signal and background events. The measured four-top-quark production cross section is found to be 26(-15)(+17) fb, with a corresponding observed (expected) significance of 1.9 (1.0) standard deviations over the background-only hypothesis. The result is combined with the previous measurement performed by the ATLAS Collaboration in the multilepton final state. The combined four-top-quark production cross section is measured to be 24(-6)(+7) fb, with a corresponding observed (expected) signal significance of 4.7 (2.6) standard deviations over the background-only predictions. It is consistent within 2.0 standard deviations with the Standard Model expectation of 12.0 +/- 2.4 fb. %K Hadron-Hadron scattering (experiments) %K Top physics %R 10.1007/JHEP11(2021)118 %U https://arxiv.org/abs/2106.11683 %U https://doi.org/10.1007/JHEP11(2021)118 %P 118-53pp