PAIR CREATION OF BLACK-HOLES BY DOMAIN-WALLS

In this paper we study the production of pairs of neutral and charged black holes by domain walls, finding classical solutions and calculati ng their classical actions. We find that neutral black holes whose cre ation is mediated by Euclidean instantons must be produced mutually at rest with respect to one another, but for charged black holes a new t ype of instanton is possible in which after formation the two black ho les accelerate away from one another. These new types of instantons ar e not possible in Einstein-Maxwell theory with a cosmological constant . We also find that the creation of nonorientable black hole solutions can be mediated by Euclidean instantons and that in addition if one i s prepared to consider entirely Lorentzian no-boundary-type contributi ons to the path integral then mutually accelerating pairs may be creat ed even in the neutral case. Finally, we consider the production of Ka luza-Klein monopoles both by a standard cosmological term and in the p resence of a domain wall. We find that compactification is accompanied by the production of pairs of Kaluza-Klein monopoles.