Searches for new resonant phenomena in final states with two top quarks using the ATLAS detector

Many theories beyond the Standard Model predict new phenomena, such as Z′ and vector-like quarks, in final states containing top quarks. It is challenging to reconstruct and identify the decay products and model the major backgrounds. Nevertheless, such final states offer great potential to reduce the Standard Model backgrounds due to their characteristic decay signature. This presentation will summarize the recent results of top-antitop resonance searches where the top quarks decay into a lepton and jets using the full Run-2 (139 fb^-1) proton-proton collision data collected at a center-of-mass energy of √s=13 TeV with the ATLAS detector. This talk will also highlight the latest improvements gained by using a new strategy to remove the overlap between an electron and a jet. The results are interpreted using models with a heavy Z’ boson of narrow width, Kaluza-Klein gluon, and Kaluza-Klein Graviton with a large width.