Black Hole Bound State Metamorphosis
  N=4 supersymmetric string theories contain negative discriminant states whose numbers are known precisely from microscopic counting formulae. On the macroscopic side, these results can be reproduced by regarding these states as multi-centered black hole configurations provided we make certain identification of apparently distinct multi-centered black hole configurations according to a precise set of rules. In this paper we provide a physical explanation of such identifications, thereby establishing that multi-centered black hole configurations reproduce correctly the microscopic results for the number of negative discriminant states without any ad hoc assumption. 
Abhishek Chowdhury, Shailesh Lal, Arunabha Saha, Ashoke Sen
hep-th gr-qc