Measurement of the top-quark decay width in top-quark pair events in the dilepton channel at $\sqrt{s}=13$ TeV with the ATLAS detector

A direct measurement of the top-quark decay width using data collected with the ATLAS experiment at $\sqrt{s}=13$ TeV is presented. The data set, collected in the years 2015 to 2018, corresponds to an integrated luminosity of 139 $\mbox{fb\(^{-1}\)}$. The decay width is measured directly using a profile-likelihood template fit to the invariant mass distribution of a charged lepton and the corresponding $b$-jet in the dileptonic decay channel of the top-quark pair. The measured width is $\Gamma_t=1.9 \pm 0.5$ GeV, in agreement with the Standard Model prediction.