Fivebrane instantons in Calabi-Yau compactifications

Abstract

We provide the last missing piece of the complete nonperturbative description of the low energy effective action emerging from Calabi-Yau compactifications of type II string theory - NS5-brane instanton corrections to the hypermultiplet moduli space MH. We find them using S-duality symmetry of the type IIB formulation. The result is encoded in a set of holomorphic functions on the twistor space of MH and includes all orders of the instanton expansion. © 2014 American Physical Society.