Search for Supersymmetry with R-parity violation in leptonic final states with the ATLAS detector at 13 TeV center-of-mass energy

Supersymmetry with R-parity violation, where the lightest supersymmetric particle can decay into Standard Model particles is an attractive target for collider-based searches for physics beyond the Standard Model. In this thesis, four-lepton events are studied as a possible signature of R-parity-violating supersymmetry, using proton- proton collision events collected by the ATLAS experiment at $\sqrt{s}$ = 13 TeV. The event selection is optimized for events with low-mass collimated lepton pairs, and the viability of estimating the important $t\bar{t}Z$ background process from $t\bar{t}\gamma$ events is shown. Using the optimized selection, it is found that pair-produced charginos with masses above 1 TeV can be discovered with $3\sigma$ significance in $10~\text{fb}^{-1}$ of data.