Description |
The discovery of Mathieu moonshine in the elliptic genus of K3 allows the construction of twisted ellipitc genera to every conjugacy class of the Mathieu group M23. We show how these twisted elliptic genera play an important role in both N=2 and N=4 string compactifictions. In N=2 string compactifications they point to the existence of a class of Calabi-Yau geometries. In N=4 compactifications they are inputs to degeneracies of 1/4 BPS states, which at large values of charges are black holes. We then study properties of these states at small values of charges which provide insight to their geometric description as black holes.
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