Speaker
Description
The top quark is the heaviest known fundamental particle, making the precise determination of its properties a critical test of the Standard Model (SM) of particle physics. While the top-quark mass and decay width are closely linked within the SM framework, a simultaneous measurement of both parameters has never previously been performed by the ATLAS experiment. This talk presents the current status of an ongoing sensitivity study for the simultaneous extraction of the top-quark mass and decay width using the full LHC Run 2 proton–proton collision dataset collected by ATLAS (140fb$^{-1}$ at $\sqrt{s}=13$ TeV). The analysis targets the dilepton decay channel of the $WWbb$ final state, exploiting the sensitivity of the invariant mass distribution of charged leptons and b-jets.