A search for $R$-parity violating supersymmetry at the 13 TeV LHC

This dissertation describes a search for $R$-parity violating supersymmetry, motivated by the stringent limits set on $R$-parity conserving models from Run I and Run II of the LHC. These limits have excluded gluino masses up to approximately $2~\mathrm{Te\kern -0.1em V}$ in mass, which is the rough scale expected for supersymmetry to ``naturally'' solve the Hierarchy Problem. These constraints, however, can be evaded by considering $R$-parity violating models, in which the lightest supersymmetric particle can decay to Standard Model particles and does not produce a large missing transverse momentum signature. To avoid conflicts with experimental measurements, such as proton decay, the framework of Minimal Flavor Violation is applied, resulting in the largest $R$-parity violating coupling being between a top, bottom, and strange quark. Therefore, this search uses the pair production of gluinos that decay via $\tilde{\mathrm{g}} \to \mathrm{t}\bar{\tilde{\mathrm{t}}} \to \mathrm{tbs}$ as a benchmark model and generically looks for new physics with a signature of a single lepton, large jet and bottom quark jet multiplicities, and high sum of large-radius jet masses, without any requirement on the missing transverse momentum in an event. The search is conducted with $35.9~\mathrm{fb^{-1}}$ of $\sqrt{s} = 13~\mathrm{Te\kern -0.1em V}$ proton-proton collisions collected by the CMS experiment in 2016. The background is estimated through a maximum-likelihood fit of the $N_\mathrm{b}$ distribution across bins of jet multiplicity and sum of large-radius jet masses. No evidence of new physics is observed, and limits on a simplified model, in which gluinos decay promptly via $\tilde{\mathrm{g}} \to \mathrm{tbs}$ , are set, excluding gluino masses below $1610~\mathrm{Ge\kern -0.1em V}$ at the 95% confidence level.