WORLDBRANE ACTIONS FOR STRING SOLITONS

The space-time dynamics of recently discovered fivebrane solitons in heterotic and type II string theories are described in terms of supersymmetric low-energy field theories which live on the (5 + 1)-dimensional soliton worldbranes. Several surprising features emerge, including: the (hitherto unsuspected) existence of both chiral and non-chiral type II five-branes; spin-one gauge as well as anti-self-dual tensor zero modes; extended supersymmetry on the worldbrane. Non-renormalization theorems for supersymmetric worldbrane actions are used to argue that gauge fivebrane (and instanton) solutions to the leading-order low-energy string equation of motion correspond to exact supersymmetric solutions of the full string equation of motion.