Applications of the holographic correspondence to QCD-like theories

This thesis explores two problems where holography provides new insights into non-perturbative quantum chromodynamics (QCD). First, it develops a holographic description of baryons in single-flavor QCD, a case where standard chiral-soliton constructions fail. Building on the idea that such baryons can be viewed as quantum Hall droplets of the η′ meson, the work realizes these objects explicitly within the Witten–Sakai–Sugimoto model as charged D6-brane configurations (“Hall droplet sheets”). Their physical properties—masses, sizes, and spin–baryon number relations—are computed, and the framework is extended to related topological defects, including axionic strings, domain walls, vortons, and composite structures with possible dark-matter relevance. Second, the thesis addresses weak interaction rates in dense, strongly coupled quark matter, relevant for neutron star interiors. It derives a non-perturbative expression for these rates in terms of gauge-invariant correlators and evaluates them in a holographic model of massless quark matter. The results reveal qualitative departures from perturbative predictions, such as logarithmic suppression at high chemical potential. Overall, the thesis demonstrates the usefulness of holography in tackling strong-coupling problems in QCD, from baryon structure to neutron-star phenomenology.