Duality Symmetry and the Cardy Limit
Abstract
We study supersymmetric and non-supersymmetric extremal black holes obtained in Type IIA string theory compactified on K3 X T^2, with duality group O(6,22,Z) X SL(2,Z). In the Cardy limit an internal circle combines with the AdS_2 component in the near horizon geometry to give a BTZ black hole whose entropy is given by the Cardy formula. We study black holes carrying D0-D4 and D0-D6 brane charges. We find, both in the supersymmetric and non-supersymmetric cases, that a generic set of charges cannot be brought to the Cardy limit using the duality symmetries. In the non-supersymmetric case, unlike the supersymmetric one, we find that when the charges are large, a small fractional change in them always allows the charges to be taken to the Cardy limit. These results could lead to a microscopic determination of the entropy for extremal non-supersymmetric black holes, including rotating cases like the extreme Kerr black hole in four dimensions.
Cite
@article{arxiv.0711.4671,
title = {Duality Symmetry and the Cardy Limit},
author = {Suresh Nampuri and Prasanta K. Tripathy and Sandip P. Trivedi},
journal= {arXiv preprint arXiv:0711.4671},
year = {2009}
}
Comments
46 pages, Latex, Some comments added in Introduction and Conclusions. Minor changes made in sections 3.4 and 5