Topological symmetry breaking: Domain walls and partial instability of chiral edges

In two-dimensional topological systems chiral edges may exhibit a spectral change due to the formation of a Bose condensate and partial confinement in the bulk according to the topological symmetry breaking (TSB) mechanism. We analyze in detail what happens in the bulk as well as on the edge for a set of simple c = 1 chiral fractional quantum Hall systems. What this paper achieves is an explicit matching of the detailed field theoretic treatments of the bulk and boundary chiral boson and Chern-Simons theories, which allows for a precise interpretation of the TSB mechanism. TSB corresponds to the spontaneous breaking of a global discrete symmetry both in the bulk and on the edge and therefore to the appearance of domain walls in the bulk that may terminate in kinks on the edge. The walls, however, are locally metastable and break if a confined particle-hole pair is created. We list the c = 1 chiral models for which this type of instability may occur.