Search for Resonant Leptoquark Production Coupling to an Electron and a b-Quark using Run 2 pp Collision Data of the ATLAS Experiment

This master thesis sets an improved expected exclusion limit on a scalar $\tilde{S}_1$ Leptoquark model solely coupling to an electron and a \bquark as part of an ongoing research by ATLAS. The exclusion limit is gained by searching for a resonant Leptoquark production using full Run~2\xspace data of the ATLAS experiment which corresponds to a proton-proton collision with a center-of-mass energy of $\sqrt{s}=13$ TeV and an integrated luminosity of 140 $\text{fb}^{-1}$. Additionally, the simulation of the signal model uses a lepton parton distribution function and has a next-to-leading-order signal precision. This next-to-leading-order precision leads to the production of final states with one and two leptons motivating a search in both final states. After optimizing the exclusion significance in both cases separately, they are recombined in a statistical analysis. The results of this thesis leads to the conclusion that the ongoing resonant search is capable of excluding new regions. These new expected exclusion limits range from Leptoquarks with masses of 1.8 TeV and a coupling $\lambda$ of 1.2 to Leptoquarks with masses of 2.6 TeV and a coupling $\lambda$ of 3.5 at a 95% confidence limit.