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v3.3.4
Abstract:
Top quarks, the heaviest elementary particles carrying colour charges, are considered to be attractive candidates for probing the quark-gluon
plasma produced in relativistic heavy-ion collisions. In such collisions, top-quark production is expected to be sensitive to nuclear modifications of parton distribution functions at high Bjoerken-x values, which are difficult to access experimentally using other available probes. In 2016, the ATLAS experiment recorded proton-lead collisions at centre-of-mass energy of 8.16 TeV per nucleon pair, corresponding to an integrated luminosity of 165 nb-1. In this talk the first measurement of the inclusive cross section of top-quark pair production in dilepton and lepton+jet decay modes with the ATLAS detector will be presented. The significance in both channels exceeds 5 standard deviations, resulting in the first observation of top-quark pair production in the dilepton channel in proton-lead collisions. The total relative uncertainty amounts to 9%, which makes it the most precise top-quark pair cross-section measurement in heavy-ion collisions to date. Comparisons to predictions based on the state-of-the-art nuclear modifications to PDFs will be shown. Prospects for top-quark pair measurements in lead-lead collisions will also be discussed.
Important: This seminar is held in building D-11 room 104.