Suresh Govindarajan

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We consider D-branes wrapped around supersymmetric cycles of Calabi-Yau manifolds from the viewpoint of N = 2 Landau-Ginzburg models with boundary as well as by consideration of boundary states in the corresponding Gepner models. The Landau-Ginzburg approach enables us to provide a target space interpretation for the boundary states. The boundary states are(More)
Motivation There has been tremendous progress in providing a microscopic counting of states that contribute to the entropy of supersymmetric black holes. More generally, one is interested in understanding the number of BPS states in different contexts such as chiral primaries in CFT's, black hole entropy. As the amount of supersymmetry is reduced, these(More)
We show that the generating function of electrically charged 1 2-BPS states in N = 4 supersymmetric CHL Z N orbifolds of the heterotic string on T 6 are given by multiplicative η-products. The η-products are determined by the cycle shape of the corresponding symplectic involution in the dual type II picture. This enables us to complete the construction of(More)
We present a method based on mutations of helices which leads to the construction (in the large volume limit) of exceptional coherent sheaves associated with the (a l a = 0) orbits in Gepner models. This is explicitly verified for a few examples including some cases where the ambient weighted projective space has singularities not inherited by the(More)