General Relativistic Solitons (II)
  We investigate the possible existence of non-topological solitons in string-like theories, or in other completions of Einstein theory, by examining a simple extension of standard theory that describes a non-linear scalar field interacting with the Einstein, Maxwell and Weyl (dilaton) fields. The Einstein and Maxwell couplings are standard while the dilatonic coupling is taken to agree with string models. The non-linear scalar potential is quite general. It is found to be impossible to satisfy the dilatonic boundary conditions. Excluding the dilaton field we find a variety of solitonic structures differing in ways that depend on the non-linear potential. In general the excited states exhibit a discrete mass spectrum. At large distances the gravitational field approaches the Reissner-Nordstrom solution. 
A. C. Cadavid and R. J. Fikelstein