Measurement of the top-quark pole mass in dileptonic + 1-jet events at TeV with the ATLAS experiment

A measurement of the top-quark pole mass is presented in events with an additional jet, + 1-jet, produced in $\textit{pp}$ collisions at TeV. The data sample, recorded with the ATLAS experiment during Run 2 of the LHC, corresponds to an integrated luminosity of 140 fb . Events with one electron and one muon of opposite electric charge in the final state are selected to measure the + 1-jet differential cross-section as a function of the inverse of the invariant mass of the + 1-jet system. Iterative Bayesian Unfolding is used to correct the data to enable comparison with fixed-order calculations at next-to-leading-order accuracy in the strong coupling. The process , where top quarks are taken as stable particles, and the process , which includes top-quark decays to the dilepton final state and off-shell effects, are considered. The top-quark mass is extracted using a $\textit{χ}$ fit of the unfolded normalized differential cross-section distribution. The results obtained with the 2 → 3 and 2 → 7 calculations are compatible within theoretical uncertainties, providing an important consistency check. The more precise determination is obtained for the 2 $\textit{→}$ 3 measurement: GeV, which is in good agreement with other top-quark mass results.