  We prove that invisible bands associated with zeros of the single-particle
Green's function exist ubiquitously at topological interfaces of 2D Chern
insulators, dual to the chiral edge/domain-wall modes. We verify this statement
in a repulsive Hubbard model with a topological flat band, using real-space
dynamical mean-field theory to study the domain walls of its ferromagnetic
ground state. Moreover, our numerical results show that the chiral modes are
split into branches due to the interaction, and that the branches are connected
by invisible flat bands. Our work provides deeper insight into interacting
topological systems.
