2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/56334In the framework of the Closed-Time-Path formalism, we show how topological defects may arise in Quantum Field Theory as result of a localized (inhomogeneous) condensation of particles. We demonstrate our approach on two examples; kinks in the $2D λψ^{4}$ theory (both at zero and finite temperature) and vortices in the complex $4D λψ^{4} $ theory.10 pages, 1 figure. To appear in the Proceedings of the 37th International School of Subnuclear Physics, Erice, 29 Aug. - 7 Sep. 1999High Energy Physics - TheoryCondensed MatterHigh Energy Physics - PhenomenologyExactly Solvable and Integrable Systemstext