2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/48411We review our work on initial value problems in Quantum Field Theory which is based on using Schwinger's Closed Time Path formalism and a large-N expansion of the Path Integral.7 pages uses ws-p8-50x6-00.cls To be published in the proceedings of the Sixth International Conference on Path Integrals, Florence Italy, 1998 by World ScientificHigh Energy Physics - Phenomenologytext