Search for Higgs boson produced in association with a charm quark in the WW channel with the CMS detector using a modern analysis framework

The standard model (SM) of particle physics describes elementary particles with high precision. In particular, the Higgs boson and its properties remain the subject of intensive study. The Yukawa couplings to second-generation fermions are among the least constrained. This thesis presents a search for Higgs boson production in association with a charm quark (cH) as an alternative probe of the charm Yukawa coupling in simpler event topologies. The Higgs boson decays to two W bosons, followed by $e\nu$ and $\mu\nu$ final states. This search is based on proton-proton collisions at $\sqrt{s}=$13 TeV recorded by CMS in 2016--2018, corresponding to 138 $\text{fb}^{-1}$.The analysis employs a modern framework that enables efficient data processing and supports commissioning studies of advanced heavy-flavor tagging algorithms. Inclusive event selections and multivariate techniques are applied to enhance sensitivity, particularly in separating dominant backgrounds from top-quark pair production and non-cH Higgs boson processes. Events are categorized by kinematics into signal- and background-dominated regions, which are used for signal extraction and for constraining systematic uncertainties in a maximum likelihood fit. No significant excess over the background expectation is observed. Upper limits at 95% confidence level (CL) are set on the signal strength of cH production, defined as the ratio of the measured yield to the SM expectation. The observed (expected) limit is 1065 (506). When combined with the previous search for cH in the diphoton decay channel of the Higgs boson, the observed (expected) limit is 257 (281), which is interpreted as constraints on the value of $\kappa_c$, $|\kappa_c| <$47 (51). This combination yields the most stringent constraints on cH production to date.