Two-Dimensional Self-Consistent Quantum-Corrected Geometries with a   Constant Dilaton Feld
  It is argued that the existence of constant dilaton field solutions is a generic feature of string-inspired dilaton gravity. Such solutins arise in the extreme limit of black hole metrics. It is shown that in a strong coupling region quantum effects give rise to two horizons in thermal equilibrium that has no classical counterpart. 
O. B. Zaslavskii