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Creators/Authors contains: "Bulanowska, W E"

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  1. ; ; ; ; ; ; ; ; ; ; et al (, Physical Review Letters)
    Top-quark pair production is observed in lead–lead ( Pb + Pb ) collisions at s 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 σ t t ¯ = 3.6   − 0.9 + 1.0 ( stat )   − 0.5 + 0.8 ( syst )     μ 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 preequilibrium stage of the quark-gluon plasma at very high energy densities, similar to the conditions present in the early Universe. © 2025 CERN, for the ATLAS Collaboration2025CERN 
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    Free, publicly-accessible full text available April 1, 2026