Marc Tost Thesis Defense

Abstract: This thesis presents the search for a heavy boson that decays through a flavor-changing neutral current to a pair of quarks. Proton-proton collision data taken at the ATLAS detector with a center-of-mass energy of √s = 13 TeV with an integrated luminosity of 140.1 f b−1 is studied. The analysis uses a particle cloud deep learning classification algorithm to attempt to identify a previously undiscovered boson. After accounting for Standard Model backgrounds with Monte Carlo estimates, no excess events are identified. Using a binned likelihood fit, the 95% CLs upper limits on σ(pp → X) ∗ Γ(X → tc) are calculated. The results are presented for multiple signal hypotheses.