KALUZA-KLEIN DYONS IN STRING THEORY

S duality of heterotic or type II string theory compactified on a six dimensional torus requires the existence of Kaluza-Klein dyons, carryi ng winding charge. We identify the zero modes of the Kaluza-Klein mono pole solution which are responsible for these dyonic excitations, and show that we get the correct degeneracy of dyons as predicted by S dua lity. The self-dual harmonic two form on the Euclidean Taub-NUT space plays a crucial role in this construction.