{"@context":"http://schema.org","@id":"https://doi.org/10.17182/hepdata.135458.v1","@reverse":{"isBasedOn":[{"@type":"ScholarlyArticle","identifier":{"@type":"PropertyValue","propertyID":"URL","value":"https://inspirehep.net/literature/2175533"}},{"@id":"https://doi.org/10.1007/JHEP07(2023)203","@type":"JournalArticle"}]},"@type":"Dataset","additionalType":"Collection","author":{"@type":"Organization","name":"ATLAS Collaboration"},"creator":{"@type":"Organization","name":"ATLAS Collaboration"},"datePublished":"2023","description":"A search for a new heavy scalar or pseudo-scalar Higgs boson ($H/A$) produced in association with a pair of top quarks, with the Higgs boson decaying into a pair of top quarks ($H/A\\rightarrow t\\bar{t}$) is reported. The search targets a final state with exactly two leptons with same-sign electric charges or at least three leptons. The analysed dataset corresponds to an integrated luminosity of 139 fb$^{-1}$ of proton-proton collisions collected at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC. Two multivariate classifiers are used to separate the signal from the background. No significant excess of events over the Standard Model expectation is observed. The results are interpreted in the context of a type-II two-Higgs-doublet model. The observed (expected) upper limits at 95% confidence level on the $t\\bar{t}H/A$ production cross-section times the branching ratio of $H/A\\rightarrow t\\bar{t}$ range between 14 (10) fb and 6 (5) fb for a heavy Higgs boson with mass between 400 GeV and 1000 GeV, respectively. Assuming that only one particle, either the scalar $H$ or the pseudo-scalar $A$, contributes to the $t\\bar{t}t\\bar{t}$ final state, values of $\\tan\\beta$ below 1.2 or 0.5 are excluded for a mass of 400 GeV or 1000 GeV, respectively. These exclusion ranges increase to $\\tan\\beta$ below 1.6 or 0.6 when both particles are considered.","hasPart":[{"@id":"https://doi.org/10.17182/hepdata.135458.v1/t1","@type":"Dataset","description":"Pre-fit comparison between data and background in the baseline SR for two of the variables used as input for the...","name":"Figure 2a"},{"@id":"https://doi.org/10.17182/hepdata.135458.v1/t2","@type":"Dataset","description":"Pre-fit comparison between data and background in the baseline SR for two of the variables used as input for the...","name":"Figure 2b"},{"@id":"https://doi.org/10.17182/hepdata.135458.v1/t3","@type":"Dataset","description":"Pre-fit comparison between data and background in the baseline SR for two of the variables used as input for the...","name":"Figure 3a"},{"@id":"https://doi.org/10.17182/hepdata.135458.v1/t4","@type":"Dataset","description":"Pre-fit comparison between data and background in the baseline SR for two of the variables used as input for 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the background-only fit to the BSM SR for the BSM pBDT distribution used...","name":"Figure 6a"},{"@id":"https://doi.org/10.17182/hepdata.135458.v1/t13","@type":"Dataset","description":"Data and post-fit background comparison obtained with the background-only fit to the BSM SR for the BSM pBDT distribution used...","name":"Figure 6b"},{"@id":"https://doi.org/10.17182/hepdata.135458.v1/t14","@type":"Dataset","description":"Observed (black solid line) and expected (black dashed line) 95% CL upper limits on the ttH/A cross-section times branching fraction...","name":"Figure 7"},{"@id":"https://doi.org/10.17182/hepdata.135458.v1/t15","@type":"Dataset","description":"Observed (red line) and expected (black dashed line) exclusion regions at 95% CL in the tan(beta) versus mass plane assuming...","name":"Figure 8a"},{"@id":"https://doi.org/10.17182/hepdata.135458.v1/t16","@type":"Dataset","description":"Observed (red line) and expected (black dashed line) exclusion regions at 95% CL in the 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