D-instanton sums for matter hypermultiplets

TL;DR

This paper computes non-perturbative D-instanton corrections to the moduli space of multiple matter hypermultiplets in type-IIA string theory compactified on Calabi-Yau threefolds, revealing a complex deformation due to infinite instantons.

Contribution

It provides the first calculation of D-instanton effects on the hypermultiplet moduli space for multiple hypermultiplets near conifold points, under specific symmetry assumptions.

Findings

D-instantons induce a non-trivial deformation of the moduli space metric

The deformation is computed in the hyper-Kähler limit without gravitational corrections

Infinite D-instantons significantly modify the hypermultiplet moduli space geometry

Abstract

We calculate some non-perturbative (D-instanton) quantum corrections to the moduli space metric of several (n>1) identical matter hypermultiplets for the type-IIA superstrings compactified on a Calabi-Yau threefold, near conifold singularities. We find a non-trivial deformation of the (real) 4n-dimensional hypermultiplet moduli space metric due to the infinite number of D-instantons, under the assumption of n tri-holomorphic commuting isometries of the metric, in the hyper-K"ahler limit (i.e. in the absence of gravitational corrections).