EXACT PHYSICAL BLACK-HOLE STATES IN GENERIC 2-D DILATON GRAVITY

The quantum mechanics of black holes in generic 2-D dilaton gravity is considered, The Hamiltonian surface terms are derived for boundary co nditions corresponding to an eternal black hole with slices on the int erior ending on the horizon bifurcation point. The quantum Dirac const raints are solved exactly for these boundary conditions to yield physi cal eigenstates of the energy operator. The solutions are obtained in terms of geometrical phase space variables that were originally used b y Cangemi, Jackiw and Zwiebach in the context of string inspired dilat on gravity. The spectrum is continuous in the Lorentzian sector, but i n the Euclidean sector the thermodynamic entropy must be 2 pi n/G wher e n is an integer The general class of models considered contains as s pecial cases string inspired dilaton gravity, Jackiw-Teitelboim gravit y and spherically symmetry gravity.