A new class of $(2+1)$-d topological superconductor with $\mathbbZ_8$ topological classification

The classification of topological states of matter depends on spatial dimension and symmetry class. For non-interacting topological insulators and superconductors the topological classification is obtained systematically and nontrivial topological insulators are classified by either integer or $Z_2$. The classification of interacting topological states of matter is much more complicated and only special cases are understood. In this paper we study a new class of topological superconductors in $(2+1)$ dimensions which has time-reversal symmetry and a $\mathbbZ_2$ spin conservation symmetry. We demonstrate that the superconductors in this class is classified by $\mathbbZ_8$ when electron interaction is considered, while the classification is $\mathbbZ$ without interaction.