{"@context":"http://schema.org","@id":"https://doi.org/10.17182/hepdata.156982.v1","@reverse":{"isBasedOn":[{"@type":"ScholarlyArticle","identifier":{"@type":"PropertyValue","propertyID":"URL","value":"https://inspirehep.net/literature/2849226"}},{"@id":"https://doi.org/10.1103/PhysRevLett.134.142301","@type":"JournalArticle"}]},"@type":"Dataset","additionalType":"Collection","author":{"@type":"Organization","name":"ATLAS Collaboration"},"creator":{"@type":"Organization","name":"ATLAS Collaboration"},"datePublished":"2025","description":"Top-quark pair production is observed in lead-lead (Pb+Pb) collisions at $\\sqrt{s_\\mathrm{NN}}=5.02$ TeV at the Large Hadron Collider with the ATLAS detector. The data sample was recorded in 2015 and 2018, amounting to an integrated luminosity of 1.9 nb$^{-1}$. Events with exactly one electron and one muon and at least two jets are selected. Top-quark pair production is measured with an observed (expected) significance of 5.0 (4.1) standard deviations. The measured top-quark pair production cross-section is $\\sigma_{t\\bar{t}} = 3.6\\;^{+1.0}_{-0.9}\\;\\mathrm{(stat.)}\\;^{+0.8}_{-0.5}\\;\\mathrm{(syst.)} ~\\mathrm{\\mu b}$, with a total relative uncertainty of 31%, and is consistent with theoretical predictions using a range of different nuclear parton distribution functions. The observation of this process consolidates the evidence of the existence of all quark flavors in the pre-equilibrium stage of the quark-gluon plasma at very high energy densities, similar to the conditions present in the early universe.","hasPart":[{"@id":"https://doi.org/10.17182/hepdata.156982.v1/t1","@type":"Dataset","description":"The figure shows the post-fit distribution of events as a function of the dilepton invariant mass ($m_{e\\mu}$), in lead-lead (Pb+Pb)...","name":"Postfit yields in the SR1 region"},{"@id":"https://doi.org/10.17182/hepdata.156982.v1/t2","@type":"Dataset","description":"The figure shows the post-fit distribution of events as a function of the dilepton invariant mass ($m_{e\\mu}$), in lead-lead (Pb+Pb)...","name":"Postfit yields in the SR2 region"},{"@id":"https://doi.org/10.17182/hepdata.156982.v1/t3","@type":"Dataset","description":"The impact of systematic uncertainties on the fitted signal-strength parameter $\\hat{\\mu}$ for the combined fit of all channels. Only the...","name":"Nuisance parameter ranking"},{"@id":"https://doi.org/10.17182/hepdata.156982.v1/t4","@type":"Dataset","description":"Breakdown of relative systematic uncertainties in the measured ${t\\bar{t}}$ cross-section. The quoted uncertainties are obtained by repeating the fit with...","name":"Grouped impact table for signal strength"},{"@id":"https://doi.org/10.17182/hepdata.156982.v1/t5","@type":"Dataset","description":"The figure shows the measurement of the top quark pair production cross-section, $\\sigma_{t\\bar{t}}$, in lead-lead (Pb+Pb) collisions at a center-of-mass...","name":"Fitted cross section"}],"identifier":[{"@type":"PropertyValue","propertyID":"HEPDataRecord","value":"https://www.hepdata.net/record/ins2849226?version=1"},{"@type":"PropertyValue","propertyID":"HEPDataRecordAlt","value":"https://www.hepdata.net/record/156982"}],"inLanguage":"en","name":"Observation of top-quark pair production in lead-lead collisions at $\\sqrt{s_\\mathrm{NN}}=5.02$ TeV with the ATLAS detector","provider":{"@type":"Organization","name":"HEPData"},"publisher":{"@type":"Organization","name":"HEPData"},"url":"https://www.hepdata.net/record/ins2849226?version=1","version":1}