non-BPS walls of marginal stability

Abstract

We explore the properties of non-BPS multi-centre extremal black holes in ungauged N=2 supergravity coupled to n_v vector multiplets, as described by solutions to the composite non-BPS linear system. After setting up an explicit description that allows for arbitrary non-BPS charges to be realised at each centre, we study the structure of the resulting solutions. Using these results, we prove that the binding energy of the composite is always positive and we show explicitly the existence of walls of marginal stability for generic choices of charges. The two-centre solutions only exist on a hypersurface of dimension n_v+1 in moduli space, with an n_v-dimensional boundary, where the distance between the centres diverges and the binding energy vanishes.