Symmetric topological Mott insulator and phase transition in 1d system

Topological band insulator and Mott insulator are two independent topics in condensed matter physics. In this work we are interested in a new phase which combine the properties of both. Topological Mott insulator was discussed before, but was mainly restricted to interaction driven symmetry breaking state, which is essentially a band insulator in mean field level. Here we propose symmetric topological Mott insulator (STMI) which is beyond any Hartree Fock mean field or Slater determinant description. Using a 1d bilayer chain model, we identify two distinct symmetric phases characterized by different topological indexes. We further study the quantum phase transition between them and propose a critical theory describing this transition.