Measurement of the top quark mass with the ATLAS detector using $t\bar{t}$ events with a high transverse momentum top quark

TL;DR

This paper reports a highly precise measurement of the top quark mass using high transverse momentum top quark events in proton-proton collisions at 13 TeV with the ATLAS detector, employing a novel analysis method to reduce uncertainties.

Contribution

The study introduces a new approach using large-radius jet reconstruction and multiple observables to improve the precision of top quark mass measurement in the lepton-plus-jets channel.

Findings

Top quark mass measured as 172.95 GeV with 0.53 GeV uncertainty.

Achieved the most precise ATLAS single-channel top mass measurement.

Method reduces systematic uncertainties in top mass determination.

Abstract

The mass of the top quark is measured using top-antitop-quark pair events with high transverse momentum top quarks. The dataset, collected with the ATLAS detector in proton--proton collisions at $\sqrt{s}=13$ TeV delivered by the Large Hadron Collider, corresponds to an integrated luminosity of 140 fb$^{-1}$. The analysis targets events in the lepton-plus-jets decay channel, with an electron or muon from a semi-leptonically decaying top quark and a hadronically decaying top quark that is sufficiently energetic to be reconstructed as a single large-radius jet. The mean of the invariant mass of the reconstructed large-radius jet provides the sensitivity to the top quark mass and is simultaneously fitted with two additional observables to reduce the impact of the systematic uncertainties. The top quark mass is measured to be $m_t = 172.95 \pm 0.53$ GeV, which is the most precise ATLAS measurement from a single channel.