Feasibility Study for Observation of the ttZ(Z → τ τ ) Process

The goal of this project was to investigate the feasibility of measuring the t¯tZ process where the Z boson decays to τ +τ −, a rare and previously unmeasured channel. Our analysis was performed using simulated data corresponding to the full ATLAS Run 2 dataset, representing an integrated luminosity of 140 fb$^{−1}$ at $ \sqrt{s}=13 TeV$. This required distinguishing the signal from dominant background processes such as $t\bar{t}Z$ (non-$\tau \bar{\tau}$ ), $t\bar{t}$H, Z+jets, and W +jets.