UCLA

This thesis investigates flux tubes as probes of emergent phenomena in strongly coupled quantum field theories. Combining analytical techniques and numerical modeling, we study the structure and dynamics of vortex strings in several variants of the Abelian Higgs model (AHM) in~$3+1$ dimensions. These systems arise in settings ranging from magnetic vortices in Ginzburg-Landau superconductors to confining strings in deformed Seiberg-Witten (SW) theory. A central focus is the large-flux limit in which the rich internal structure of vortex strings becomes analytically tractable. In the AHM that arises in the context of deformed SW theory, we find that giant vortex strings exhibit a nontrivial pattern of phases and transitions. This structure becomes especially transparent in the large vorticity limit and bears a striking resemblance to wall-crossing phenomena for kink solutions in two-dimensional supersymmetric theories. We also investigate the low-energy worldsheet spectra of superconducting strings. In the minimal AHM, we identify a light pseudoscalar mode in the regime, where parallel strings repel. Comparing this spectrum with lattice results for Yang-Mills flux tubes, we conclude that the minimal AHM does not provide a compelling dual description of confining strings in pure Yang-Mills theory. Together, these results reveal the rich internal dynamics of vortex strings in analytically controlled models while clarifying both the potential and the limitations of Abelian Higgs models as effective dual descriptions of pure Yang-Mills flux tubes.