Precision counting of small black holes

Abstract

It has recently been proposed that a class of supersymmetric higher-derivative interactions in N ≤ 2 supergravity may encapsulate an infinite number of finite size corrections to the microscopic entropy of certain supersymmetric black holes. If this proposal is correct, it allows one to probe the string theory description of black-hole micro-states to far greater accuracy than has been possible before. We test this proposal for ''small'' black holes whose microscopic degeneracies can be computed exactly by counting the corresponding perturbative BPS states. We also study the ''black hole partition sum'' using general properties of of BPS degeneracies. This complements and extends our earlier work in [1].