Measurements of ttbar differential cross-sections in the all-hadronic channel using highly boosted top quarks with the ATLAS detector at sqrt(s)= 13 TeV

Measurements of differential cross-sections of highly-boosted top-quark pair production as a function of top-quark and ttbar system kinematic observables are made using proton--proton collisions at a centre-of-mass energy of √s=13 TeV. The data set corresponds to an integrated luminosity of 36.1 fb^{−1}, recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. Events with two large-radius jets in the final state, one with transverse momentum p_{T}>500 GeV and a second with p_{T}>350 GeV, are used for the measurement. The top-quark candidates are separated from the multijet background using jet substructure information and association to a b-tagged jet. The measured spectra are corrected for detector effects to a particle-level fiducial phase space and a parton-level limited phase space, and are compared to several Monte Carlo simulations. The cross-section for tt¯ production in the fiducial phase-space region is 292±7 (stat)±76(syst) fb, to be compared to the theoretical prediction obtained using the POWHEG+Pythia8 generator of 392±36(th) fb.