Degeneracy and continuous deformations of supersymmetric domain walls

In a wide class of supersymmetric theories degenerate families of the BPS-saturated domain walls exist. The internal structure of these walls can continuously vary, without changing the wall tension. This is described by hidden parameters (collective coordinates). Differentiating with respect to the collective coordinates one gets a set of the bosonic zero modes localized on the wall. Neither of them is related to the spontaneous breaking of any symmetry. Through the residual $1/2$ of supersymmetry each bosonic zero mode generates a fermionic partner.