Measurement of the top quark mass with the ATLAS detector using 𝑡�𝑡� events with a high transverse momentum top quark

Abstract

The mass of the top quark is measured using top-quark-top-antiquark pair events with high transverse momentumtop quarks. The dataset, collected with the ATLAS detector in proton-proton collisions atSQUARE ROOT𝑠 = 13 TeV deliveredby the Large Hadron Collider, corresponds to an integrated luminosity of 140 fb-1. The analysis targets events inthe lepton-plus-jets decay channel, with an electron or muon from a semi-leptonically decaying top quark and ahadronically decaying top quark that is sufficiently energetic to be reconstructed as a single large-radius jet. Themean of the invariant mass of the reconstructed large-radius jet provides the sensitivity to the top quark massand is simultaneously fitted with two additional observables to reduce the impact of the systematic uncertainties.The top quark mass is measured to be 𝑚𝑡 = 172.95 +- 0.53 GeV, which is the most precise ATLAS measurementfrom a single channel.