Precision Measurements of the Properties of the Higgs Boson Using the CMS Detector

The Higgs Boson, first discovered in 2012, was the first and only new fundamental particle found at the LHC since data taking began in 2009. Even promising alternative models of new physics, such as Super Symmetry, have yet to be experimentally confirmed 15 years after the LHC first started collecting data. With the apparent lack of new physics at the TeV scale, model independent, precision measurements of the Higgs boson may be the only way to provide hints about the nature of physics beyond the standard model. Effective field theory (EFT) provides a model independent framework for searching for new physics in this era of precision measurements. Rather than looking for new resonances, the effects of beyond standard model physics are characterized by small deviations in observables from the standard model prediction or enhanced rates of rare processes.

In this thesis, I will present various studies and analyses involving precision measurements of the Higgs boson's properties. First, I will detail various contributions to the tracker alignment, which is crucial for precision measurements at the LHC. Then I will present phenomenological studies applied to LHC data including contributions to the various tools (specifically JHUGen and MELA) that make my analyses and many others on CMS possible. I will show results targeting the $\gamma$H production process and constraints on the Yukawa couplings of light quarks. Finally, I will present simultaneous constraints on eight anomalous couplings of the Higgs boson to vector bosons using the four-lepton final state. Results are interpreted in the EFT framework using data collected by the CMS experiment during Run 2 and Run 3 of the LHC. These results represent the most model independent constraints on the Higgs boson couplings to date and are the first constraints on anomalous couplings in this final state including the LHC Run-3 dataset.