Search for four-top-quark production in the single-lepton and opposite-sign dilepton final states in pp collisions at √s = 13 TeV with the ATLAS detector Aaboud, M. Aguilar Saavedra, Juan Antonio Atlas Collaboration A search for four-top-quark production, tt¯tt¯, is presented. It is based on proton-proton collision data with a center-of-mass energy s√ = 13 TeV collected by the ATLAS detector at the Large Hadron Collider during the year 2015 and 2016, corresponding to an integrated luminosity of 36.1 fb−1. Data are analyzed in both the single-lepton and opposite-sign dilepton channels, characterized by the presence of one or two isolated electrons or muons with high-transverse momentum and multiple jets. A data-driven method is used to estimate the dominant background from top-quark pair production in association with jets. No significant excess above the Standard Model expectation is observed. The result is combined with the previous same-sign dilepton and multilepton searches carried out by ATLAS and an observed (expected) upper limit of 5.3 (2.1) times the four-top-quark Standard Model cross section is obtained at 95% confidence level. Additionally, upper limit on anomalous four-top-quark production cross section is set in the context of an effective field theory model. 2020-03-10T08:42:48Z 2020-03-10T08:42:48Z 2019-03-26 info:eu-repo/semantics/article Berlendis, S., Cheu, E., Delitzsch, C. M., Johns, K. A., Jones, S., Lampl, W., ... & Rutherfoord, J. P. (2019). Search for four-top-quark production in the single-lepton and opposite-sign dilepton final states in pp collisions at root s= 13 TeV with the ATLAS detector. http://hdl.handle.net/10481/60162 10.1103/PhysRevD.99.052009 eng http://creativecommons.org/licenses/by/3.0/es/ info:eu-repo/semantics/openAccess Atribución 3.0 España American Physical Society