SUBLEADING CONTRIBUTIONS FROM INSTANTON CORRECTIONS IN N=2 SUPERSYMMETRIC BLACK-HOLE ENTROPY

We present subleading corrections to the N = 2 supersymmetric black ho le entropy. These subleading contributions correspond to instanton cor rections of the Type II string theory. In particular we consider an ax ion free black hole solution of low-energy effective Type II string th eory. We present a procedure to include successive all instanton corre ctions. Expanding these corrections at particular points in moduli spa ce yields polynomial and logarithmic instanton corrections to the clas sical black hole entropy. We comment on a microscopic interpretation o f these instanton corrections and find that the logarithmic correction s correspond to subleading terms in the degeneracy of the spectrum of an underlying quantum theory. (C) 1997 Published by Elsevier Science B .V.