Measurements of differential cross-sections for top-quark pair production in association with additional jets in highly boosted events using the ATLAS detector

Top anti-top pair production at the Large Hadron Collider is often observed in the presence of additional high energy radiation. Similarly abundant top-quark pair production allows us to probe high transverse momentum top quarks. These proceedings showcase recent top-quark pair production cross-section measurements with a high energy (boosted) top-quark using proton-proton collision events at a centre-of-mass energy of 13 TeV recorded by the ATLAS detector from 2015 to 2018. The results are compared to different QCD predictions showcasing how suited current theories are to estimating complex, multi-scale, and above leading order processes. Differential top-quark pair cross-section measurements as functions of various event kinematic properties are presented, using events with a high transverse momentum large-R jet, one muon or electron and at least two $b$-tagged jets in the final-state. The sensitivity of these measurements to beyond Standard Model physics effects is also probed by imposing simultaneous limits on two effective field theory operators.