Aad, G.Abbott, B.Abbott, D.C.Abed Abud, A.Abeling, K.Abhayasinghe, D.K.Abidi, S.H.AbouZeid, O.S.Abraham, N.L.Abramowicz, H.Albert, JustinAnelli, Christopher R.Carlson, Evan MichaelChiu, Y.H.Ghasemi Bostanabad, M.Hamano, KenjiKay, E. F.Keeler, RichardKowalewski, RobertLefebvre, Michelet al.2021-01-262021-01-2620202020Aad, G., Abbott, B., Abbott, D. C., Abed Abud, A., Abeling, K., Abhayasinghe, D. K., … Zwalinski, L. (2020). Search for tt¯ resonances in fully hadronic final states in pp collisions at √s = 13 TeV with the ATLAS detector. Journal of High Energy Physics, 2020(10). https://doi.org/10.1007/JHEP10(2020)061https://doi.org/10.1007/JHEP10(2020)061http://hdl.handle.net/1828/12596This paper presents a search for new heavy particles decaying into a pair of top quarks using 139 fb−1 of proton-proton collision data recorded at a centre-of-mass energy of s√ = 13 TeV with the ATLAS detector at the Large Hadron Collider. The search is performed using events consistent with pair production of high-transverse-momentum top quarks and their subsequent decays into the fully hadronic final states. The analysis is optimized for resonances decaying into a tt¯ pair with mass above 1.4 TeV, exploiting a dedicated multivariate technique with jet substructure to identify hadronically decaying top quarks using large-radius jets and evaluating the background expectation from data. No significant deviation from the background prediction is observed. Limits are set on the production cross-section times branching fraction for the new Z′ boson in a topcolor-assisted-technicolor model. The Z′ boson masses below 3.9 and 4.7 TeV are excluded at 95% confidence level for the decay widths of 1% and 3%, respectively.enJet substructureBeyond Standard ModelHadron-Hadron scattering (experiments)Heavy quark productionJetsArticleDepartment of Physics and Astronomy