Playing the Higgs Field: Using the Higgs Boson to Search for New Physics with the ATLAS Detector

This dissertation presents the Higgs boson as a tool to search for physics beyond the Standard Model through its interactions with hypothetical particles.  Two searches are presented, both using proton–proton collision data collected by the ATLAS detector during Run 2 of the Large Hadron Collider.  First, the Higgs boson’s couplings to dark matter candidates are investigated by analyzing fully and partially invisible decay channels.  Second, interactions between the Higgs and new high-mass scalar bosons are probed to explore extensions of the scalar sector.  By constraining these couplings, this work aims to reveal signatures of new physics and guide future experimental searches at high-energy colliders.