Strong coupling expansion in a correlated three-dimensional topological insulator

Motivated by recent studies which show that topological phases may emerge in strongly correlated electron systems, we theoretically study the strong electron correlation effect in a three-dimensional topological insulator, where the effective Hamiltonian can be described by the Wilson fermions. We adopt a 1/r long-range Coulomb interaction as the interaction between the bulk electrons. Based on the U(1) lattice gauge theory, the strong coupling expansion is applied by assuming that the effective interaction is strong. It is shown that the effect of the Coulomb interaction is equivalent to the renormalization of the bare mass of the Wilson fermions and, as a result, the topological insulator phase survives in the strong coupling limit.