2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/147464A brief review is given of a new method for studying the critical behavior of quantum impurity problems, based on conformal field theory techniques, which I developed with Andreas Ludwig. Some results on the overscreened Kondo problem are reviewed. It is shown that the simple open and periodic fixed points, which occur in quantum spin chain impurity models, are related to each other by fusion.Latex, 15 pages, LaTex, UBCTP-93-25, hard copy of figures available from maxwell@physics.ubc.caCondensed MatterHigh Energy Physics - Theorytext