Black Holes from Non-Abelian Toda Theories
  NON-ABELIAN TODA THEORIES are shown to provide EXACTLY SOLVABLE conformal systems in the presence of a BLACK HOLE which may be regarded as describing a string propagating in target space with a black-hole metric. These theories are associated with non-canonical $\bf Z$-gradations of simple algebras, where the gradation-zero subgroup is non-abelian. They correspond to gauged WZNW models where the gauge group is nilpotent and are thus basically different from the ones currently considered following Witten. The non-abelian Toda potential gives a cosmological term which may be exactly integrated at the classical level. 
Jean-Loup Gervais and Mikhail V. Saveliev