Search for Standard Model Production of Four Top Quarks in Compact Muon Solenoid Detector and Designing Neural Networks for Top Quark Yukawa Coupling Measurement from Four Top Quark Production

The production of four top quarks has been predicted by the Standard Model (SM) and has been considered as one of its important tests. The measurements obtainable from this production, such as its cross section, can be compared with predictions provided by SM. This comparison can determine whether SM is adequate to explain this phenomenon. The four-top quark production is also sensitive to the coupling strength between the top quark and the Higgs boson, also known as the top Yukawa coupling. By considering Feynman diagrams for this production, this coupling value affects both its cross section and the kinematics of the top quarks within the production. These changes caused by top Yukawa coupling offer potential new information for novel techniques, such as neural networks, to measure the coupling value. This dissertation describes the combination of four-top quark production searches in different final states, along with a study of the use of neural networks for the measurement of top quark Yukawa coupling.