Defects and bulk perturbations of boundary Landau-Ginzburg orbifolds

We propose defect lines as a useful tool in the study of bulk perturbations of conformal field theory, in particular in the analysis of the induced renormalisation group flows of boundary conditions. As a concrete example we study bulk perturbations of N = 2 supersymmetric minimal models. To these perturbations we associate a special class of defects between the respective UV and IR theories, whose fusion with boundary conditions indeed reproduces the behaviour of the latter under the corresponding RG flows.