Defects in Higher-Dimensional Quantum Field Theory

The present work is addressed to defects and boundaries in quantum
field theory considering the application to AdS/CFT correspondence.
We examine interactions of fermions with spins localised on these
boundaries. Therefore, an algebra method is emphasised adding
reflection and transmission terms to the canonical quantisation
prescription. This method has already been applied to bosons in two
space-time dimensions before. We show the possibilities of such
reflection-transmission algebras in two, three, and four
dimensions. We compare with models of solid state physics as well
as with the conformal field theory approach to the Kondo effect.