ENTROPY AND SUPERSYMMETRY OF D-DIMENSIONAL EXTREMAL ELECTRIC BLACK-HOLES VERSUS STRING STATES

Following the work of Sen, we consider the correspondence between extr emal black holes and string states in the context of the entropy. We o btain and study properties of electrically charged black hole backgrou nds of tree level heterotic string theory compactified on a p-dimensio nal torus, for D = (10-p) = 4,...,9. We study in particular a one-para meter extremal class of these black holes, the members of which are sh own to be supersymmetric. We find that the entropy of such an extremal black hole, when calculated at the stringy stretched horizon, scales in such a way that it can be identified with the entropy of the elemen tary string state with the corresponding quantum numbers.