An Effective Field Theory for the Spinless p-wave Superconductor

Abstract

We construct effective field theories for superconductors, that are powerful enough to describe low lying sub gap fermion modes localized to vortex cores, and at the same time resemble topological field theories in that there are no bulk degrees of freedom. This is achieved by a kinetic term for fermions that is proportional to the vortex topological charge, and thus vanish in the bulk. We study the case of a spin-less two-dimensional $p_x + ip_y$ superconductor in some detail, and show that the the subgap fermionic spectrum in a single vortex, including the zero mode, has the same features as those obtained from microscopic models. We also show, that in the topological scaling limit our theory becomes a bona fide topological field theory which retains the Majorana modes at the vortex cores, and correctly describes the non-Abelian statistics of such vortices.