JOURNAL OF HIGH ENERGY PHYSICS, cilt.2025, sa.12, 2025 (SCI-Expanded, Scopus)
A measurement of the top-quark pole mass m(t)(pole) t is presented in t (t) over bar events with an additional jet, t (t) over bar+ 1-jet, produced in pp collisions at root s = 13TeV. The data sample, recorded with the ATLAS experiment during Run 2 of the LHC, corresponds to an integrated luminosity of 140 fb(-1). Events with one electron and one muon of opposite electric charge in the final state are selected to measure the t (t) over bar+ 1-jet differential cross-section as a function of the inverse of the invariant mass of the t (t) over bar + 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 pp. t (t) over barj (2. 3), where top quarks are taken as stable particles, and the process pp. b (b) over barl+nu l- (nu) over barj (2. 7), which includes top-quark decays to the dilepton final state and off-shell effects, are considered. The top-quark mass is extracted using chi(2) 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. 3 measurement: m(t)(pole) = 170.7 +/- 0.3 (stat.)+/- 1.4 (syst.)+/- 0.3 (scale)+/- 0.2 (PDF circle plus alpha(S)) GeV, which is in good agreement with other top-quark mass results.