Subleading contributions from instanton corrections in N=2 supersymmetric black hole entropy

We present subleading corrections to the N = 2 supersymmetric black hole entropy. These subleading contributions correspond to instanton corrections of the Type II string theory. In particular we consider an axion free black hole solution of low-energy effective Type II string theory. We present a procedure to include successive all instanton corrections. Expanding these corrections at particular points in moduli space yields polynomial and logarithmic instanton corrections to the classical black hole entropy. We comment on a microscopic interpretation of these instanton corrections and find that the logarithmic corrections correspond to subleading terms in the degeneracy of the spectrum of an underlying quantum theory. (C) 1997 Published by Elsevier Science B.V.