UC Riverside

The thesis explores two critical aspects of particle physics, focusing on dark matter charac- teristics and top quark interactions within different contexts. The second chapter proposes a model for ultralight fermionic dark matter, examining its implications for galactic dynamics and the role of supermassive black holes. The latter chapters focus on effective field theory to probe new physics through top quark interactions in current and future colliders. In exploring top quark phenomenology at the LHC, we first analyze the effects of dimension- six operators on single top quark production associated with a Higgs boson. This analysis highlights potential deviations from Standard Model predictions, suggesting avenues for dis- covering new physics. Additionally, we investigate multi-lepton signals resulting from top quark interactions, focusing on the implications of 4-Fermi ttll contact interactions. This study segment meticulously assesses the sensitivity of various lepton channels, proposing optimized experimental strategies to enhance the detection of these interactions.