Multiple D3-instantons and mock modular forms II

Abstract : We analyze the modular properties of D3-brane instanton corrections to the hypermultiplet moduli space in type IIB string theory compactified on a Calabi-Yau threefold. In Part I, we found a necessary condition for the existence of an isometric action of S-duality on this moduli space: the generating function of DT invariants in the large volume attractor chamber must be a vector-valued mock modular form with specified modular properties. In this work, we prove that this condition is also sufficient at two-instanton order. This is achieved by producing a holomorphic action of SL(2,Z) on the twistor space which preserves the holomorphic contact structure. The key step is to cancel the anomalous modular variation of the Darboux coordinates by a local holomorphic contact transformation, which is generated by a suitable indefinite theta series. For this purpose we introduce a new family of theta series of signature (2,n-2), find their modular completion, and conjecture sufficient conditions for their convergence, which may be of independent mathematical interest.
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Soumis le : jeudi 2 novembre 2017 - 14:39:54
Dernière modification le : jeudi 11 janvier 2018 - 01:54:33

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  • HAL Id : hal-01627846, version 1
  • ARXIV : 1702.05497



Sergey Alexandrov, Sibasish Banerjee, Jan Manschot, Boris Pioline. Multiple D3-instantons and mock modular forms II. L2C:17-011. 24+24 pages. 2017. 〈hal-01627846〉



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