On the gravitational structure of elementary particles

Abstract

Gravitational Bags are spherically symmetric solutions of higher dimensional Kaluza-Klein (K-K) theories, where the compact dimensions become very large near the center of the geometry, although they are small elsewhere. K-K excitations become therefore very light when located near the center of this geometry and this appears to affect drastically the naive tower of masses spectrum of K-K theories. In the context of string theories, string excitations can be enclosed by Gravitational Bags, making them not only lighter, but also localized as observed by somebody who does not probe the central regions. Strings however can still have divergent sizes, as quantum mechanics seems to demand, since the extra dimensions blow up at the center of the geometry.