The saddle-point configuration of the symmetric ø4-model

A saddle-point configuration of the symmetric ø4-model is obtained in (2+0)-dimensions under a boundary condition such that the solution øs(x,y) represents the domain walls along x- and y-axes far from the origin. We performed a linear stability analysis of the solution øs(x,y) numerically, and we found a single unstable mode of deformation and four marginally stable modes of deformation. We conclude that there exists a four-dimensional continuous parameter family of saddle-point configurations including øs(x,y).