Interaction between domain walls in chiral p-wave superconductors

We calculate microscopically the interaction energy of domain walls separating degenerate ground states in a chiral p-wave superconductor. The interaction is mediated by the quasiparticles experiencing Andreev scattering at the domain walls. As a by-product, we derive a useful general expression for the free energy of an arbitrary nonuniform texture of the order parameter in terms of the quasiparticle scattering matrix.