{"@context":"http://schema.org","@id":"https://doi.org/10.17182/hepdata.158356.v1","@reverse":{"isBasedOn":[{"@type":"ScholarlyArticle","identifier":{"@type":"PropertyValue","propertyID":"URL","value":"https://inspirehep.net/literature/2823281"}},{"@id":"https://doi.org/10.1140/epjc/s10052-025-14041-z","@type":"JournalArticle"}]},"@type":"Dataset","additionalType":"Collection","author":{"@type":"Organization","name":"ATLAS Collaboration"},"creator":{"@type":"Organization","name":"ATLAS Collaboration"},"datePublished":"2025","description":"A search is presented for a heavy scalar ($H$) or pseudo-scalar ($A$) predicted by the two-Higgs-doublet models, where the $H/A$ is produced in association with a top-quark pair ($t\\bar{t}H/A$), and with the $H/A$ decaying into a $t\\bar{t}$ pair. Events are selected requiring exactly one or two opposite-charge electrons or muons. Data-driven corrections are applied to improve the modelling of the $t\\bar{t}$+jets background in the regime with high jet and $b$-jet multiplicities. These include a novel multi-dimensional kinematic reweighting based on a neural network trained using data and simulations. An $H/A$-mass parameterised graph neural network is trained to optimise the signal-to-background discrimination. In combination with the previous search performed by the ATLAS Collaboration in the multilepton final state, the observed upper limits on the $t\\bar{t}H/A \\rightarrow t\\bar{t}t\\bar{t}$ production cross-section at 95% confidence level range between 14 fb and 5.0 fb for an $H/A$ with mass between 400 GeV and 1000 GeV, respectively. Assuming that both the $H$ and $A$ contribute to the $t\\bar{t}t\\bar{t}$ cross-section, $\\tan\\beta$ values below 1.7 or 0.7 are excluded for a mass of 400 GeV or 1000 GeV, respectively. The results are also used to constrain a model predicting the pair production of a colour-octet scalar, with the scalar decaying into a $t\\bar{t}$ pair.","hasPart":[{"@id":"https://doi.org/10.17182/hepdata.158356.v1/t1","@type":"Dataset","description":"Post-fit distribution of the GNN score evaluated with $m_{H/A}$ = 400 GeV in the 1L region with $\\geq 10$ jets...","name":"Figure 6a"},{"@id":"https://doi.org/10.17182/hepdata.158356.v1/t2","@type":"Dataset","description":"Post-fit distribution of the GNN score evaluated with $m_{H/A}$ = 400 GeV in the 2LOS region with $\\geq8$ jets and...","name":"Figure 6b"},{"@id":"https://doi.org/10.17182/hepdata.158356.v1/t3","@type":"Dataset","description":"Post-fit distribution of the GNN score evaluated with $m_{H/A}$ = 400 GeV in the validation region in the 1L region...","name":"Figure 7a"},{"@id":"https://doi.org/10.17182/hepdata.158356.v1/t4","@type":"Dataset","description":"Post-fit distribution of the GNN score evaluated with $m_{H/A}$ = 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