Spontaneous decay of a metastable domain wall
  We consider the decay of a metastable domain wall. The transition proceeds through quantum tunneling, and we calculate in arbitrary number of dimensions the preexponential factor multiplying the leading semiclassical exponential expression for the rate of the process. We find that the effect of the motion in transverse directions reduces to a renormalization of the tension of the edge of the wall in the semiclassical exponent. This behavior is similar to the one previously found for breaking of a metastable string. However this simple property is generally lost for spontaneous decay of higher-dimensional branes. 
A. Monin and M.B. Voloshin