  We construct a class of supersymmetric vacua of type IIB string theory
describing systems of three- and seven-branes non-perturbatively completed by
brane instantons. The vacua are specified by a set of holomorphic functions
defined over a complex plane up to non-trivial U-duality monodromies around the
brane locations. In the simplest setting, the solutions can be seen as a
generalization of F-theory elliptic fibrations, where the torus fiber is
replaced by a genus two Riemann surface with periods encoding the information
on the axio-dilaton, the warp factor and the NS-NS and R-R fluxes.

High Energy Physics - Theory