2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/129806We study the spectrum of fermionic modes on cosmic string loops. We find no fermionic zero modes nor massive bound states - this implies that vortons stabilized by fermionic currents do not exist. We have also studied kink-(anti)kink and vortex-(anti)vortex systems and find that all systems that have vanishing net topological charge do not support fermionic bound modes.27 pages including 4 eps figuresHigh Energy Physics - TheoryHigh Energy Physics - Phenomenologytext