Search for the decay of Standard Model Higgs bosons to a charm quark-antiquark pair using 138 fb$^{-1}$ of CMS proton-proton collision data at $\sqrt{s}=13~$TeV

The Standard Model of particle physics describes the fundamental ways in which the particles of our universe interact. In this description, we predict that elementary particles obtain their masses through their interaction with the non-zero vacuum excitation value of the Higgs field. For fermions, the strength of these interactions is described by a Yukawa coupling between the fermions and the Higgs which exist as free parameters in the theory. As such, the only indication of these coupling strengths has previously been from our existing knowledge of the fermion masses. However, through the Large Hadron Collider we are now able to directly measure the strength of the Yukawa coupling between real Higgs boson particles and the various species of fermions. In this thesis, I present a study in which we search for a Higgs boson particle directly interacting with second generation charm quarks through the $H\rightarrow c\bar{c}$ decay mode using 138 fb$^{-1}$ of $\sqrt{s}=13$ TeV proton-proton collision data collected with the CMS detector. To perform this search, I make use of the $VH$ production mode, in which the Higgs boson is produced in association with a $W$ or $Z$ vector gauge boson. To validate the analysis strategy, a secondary search is also carried out in which the analysis framework is re-cast to search for diboson production in which a real $Z$ boson decays directly to a charm quark-antiquark pair. Through combination with the results of a second analysis team within the CMS collaboration, we produce the first study to observe the $Z\rightarrow c\bar{c}$ decay mode in a hadron collider.