Speaker
Description
The production of four top-quarks, a rare final state predicted by the Standard Model, has never been seen at the 3$\sigma$ level. Additionally, this final state may be particularly sensitive to physics beyond the Standard Model. The ATLAS search for four top-quark production using 2015-2018 data collected at $\sqrt{s} = $ 13 TeV, with a combined luminosity of 139 fb$^{-1}$, is in progress. One important aspect to improve the measurement is the optimization of variables for jets, including $b$-tagged and re-clustered jets, in order to isolate signal events from the primary $t\bar{t}$ background in the 1-lepton and dilepton opposite-sign channels. By performing profile likelihood ratio fitting, we evaluate and report the significance associated with alternative selection criteria on jet variables.
