STRINGY COSMIC STRINGS AND NONCOMPACT CALABI-YAU MANIFOLDS

We describe string vacuum configurations for which the radii (moduli) of the internal compact space vary in four-dimensional space-time, focusing on configurations which have the interpretation of cosmic strings. We will show that some of them admit Ricci-flat Kähler metrics (i.e. they correspond to noncompact Calabi-Yau manifolds), thus providing new vacuum solutions to the full string theory. One novel feature of some of these solutions is that the internal space decompactifies near the core of the cosmic string, without producing any physical singularities. © 1990.