Calculating the tension of domain wall junctions and vortices in generalized Wess-Zumino models

We study BPS saturated objects with axial geometry (wall junctions, vortices) in generalized Wess-Zumino models. It is observed that the tension of such objects is negative in general (although "exceptional" models are possible). We show how an ambiguity in the definition of central charges does not affect physical quantities, and we comment on the stability of the junctions and vortices. We illustrate these issues in two classes of models with Z_N symmetry. On the basis of analytical large N calculations and numerical calculations at finite N, we argue that the domain wall junctions in these models are indeed BPS saturated, and we calculate the junction tensions explicitly.