A Search For B-L R-Parity-Violating Scalar Top Decays With the ATLAS Experiment

This dissertation presents a search for stop pair production followed by decays to a charged lepton and a $b$ quark, using the Full Run 2 dataset collected by ATLAS. This search is motivated by a supersymmetric model with an extra local symmetry $U(1)_{B-L}$, where the stop may be the lightest supersymmetric particle and can decay promptly via an R-parity violating coupling. The search identifies events with two high-$p_{T}$ leptons (electrons or muons) and two high-$p_{T}$ jets, one of which is b-tagged as initiated by a b-quark. In the absence of an excess, limits are placed on the stop mass for different values of the branching fractions for $\tilde{t} \to e b$, $\tilde{t} \to \mu b$, and $\tilde{t} \to \tau b$.