Measurement of the top-quark pole mass in dileptonic tt¯ + 1-jet events at s=13 TeV with the ATLAS experiment

AbstraktAbstract

A measurement of the top-quark pole mass m_{t}^\text{pole} is presented in t\bar{t} events with an additional jet, t\bar{t}+1\text{-jet}, produced in pp collisions at \sqrt{s}=13 TeV. The data sample, recorded with the ATLAS experiment during Run 2 of the LHC, corresponds to an integrated luminosity of 140~\text{fb}^{-1}. Events with one electron and one muon of opposite electric charge in the final state are selected to measure the t\bar{t}+1\text{-jet} differential cross-section as a function of the inverse of the invariant mass of the t\bar{t}+1\text{-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 \to t\bar{t}j (2 \rightarrow 3), where top quarks are taken as stable particles, and the process pp \to b\bar{b}l^+\nu l^- \bar{\nu} j (2 \to 7), which includes top-quark decays to the dilepton final state and off-shell effects, are considered. The top-quark mass is extracted using a \chi^2 fit of the unfolded normalized differential cross-section distribution. The results obtained with the 2 \to 3 and 2 \to 7 calculations are compatible within theoretical uncertainties, providing an important consistency check. The more precise determination is obtained for the 2 \to 3 measurement: m_{t}^\text{pole}=170.7\pm0.3~(\text{stat.})\pm1.4~(\text{syst.})~\pm 0.3~(\text{scale})~\pm 0.2~(\text{PDF}\oplus\alpha_\text{S})~\text{GeV}, which is in good agreement with other top-quark mass results.

A measurement of the top-quark pole mass m_{t}^\text{pole} is presented in t\bar{t} events with an additional jet, t\bar{t}+1\text{-jet}, produced in pp collisions at \sqrt{s}=13 TeV. The data sample, recorded with the ATLAS experiment during Run 2 of the LHC, corresponds to an integrated luminosity of 140~\text{fb}^{-1}. Events with one electron and one muon of opposite electric charge in the final state are selected to measure the t\bar{t}+1\text{-jet} differential cross-section as a function of the inverse of the invariant mass of the t\bar{t}+1\text{-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 \to t\bar{t}j (2 \rightarrow 3), where top quarks are taken as stable particles, and the process pp \to b\bar{b}l^+\nu l^- \bar{\nu} j (2 \to 7), which includes top-quark decays to the dilepton final state and off-shell effects, are considered. The top-quark mass is extracted using a \chi^2 fit of the unfolded normalized differential cross-section distribution. The results obtained with the 2 \to 3 and 2 \to 7 calculations are compatible within theoretical uncertainties, providing an important consistency check. The more precise determination is obtained for the 2 \to 3 measurement: m_{t}^\text{pole}=170.7\pm0.3~(\text{stat.})\pm1.4~(\text{syst.})~\pm 0.3~(\text{scale})~\pm 0.2~(\text{PDF}\oplus\alpha_\text{S})~\text{GeV}, which is in good agreement with other top-quark mass results.