2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/155670Survey article on loop groups and their representations, following a course of three lectures held at the summer school "algebraic groups" at the Georg-August-Universitaet zu Goettingen, June 27--July 13, 2005. We discuss loop groups, their central extensions, and positive energy representations.18 pagesDifferential GeometryRepresentation Theorytext