Investigation of systematic uncertainties on the measurement of the top-quark mass using lepton transverse momenta

This study investigates the impact of systematic uncertainties on a top-quark mass ($m_\text{top}$) measurement in the lepton+jets channel with the ATLAS experiment at the LHC. For the study, simulated $t\bar{t}$ events with lepton+jets final states at a centre of mass energy of 8 TeV are used. In contrast to other analyses, this study is designed to exploit the dependence of the lepton kinematics on the top-quark mass, by parameterising the lepton's transverse momentum distribution with MC simulations. Due to its different systematic uncertainty, this method can potentially contribute to a more accurate measurement of $m_\text{top}$. The overall uncertainty in this study is 2.3 GeV, dominated by the current uncertainty on initial and final state radiation. Since the result depends on the modelling of the top-quark transverse momentum, it is sensitive to higher order QCD corrections. The influence of such corrections is estimated by reweighting the next-to-leading-order MC prediction by next-to-next-to-leading-order calculations. This leads to a shift in the measured top-quark mass of $-1.0 \pm 0.5$ GeV and therefore shows that higher order QCD corrections can influence the determination of $m_\text{top}$ based on lepton $p_\text{T}$ distributions.