Differential cross-section measurements of boosted top quarks at $\sqrt{s} = 13$ TeV with the ATLAS detector

Abstract: Differential cross-section measurements of highly boosted top quarks are presented. The dataset used has an integrated luminosity of $3.2$ fb$^{-1}$, recorded at a centre-of-mass energy of $\sqrt{s}=13$ TeV with the ATLAS detector at the CERN Large Hadron Collider in 2015. Events are selected in the lepton + jets channel, containing one isolated lepton and a large radius jet that is identified as originating from a top quark using substructure tagging techniques. The measured transverse momentum and absolute rapidity distributions are unfolded to remove detector effects and compared to a range of Monte Carlo simulations. The transverse momentum distribution shows that all Monte Carlo generators used predict a harder spectrum than observed in data, while the rapidity distribution agrees well between MC and data.