D-instantons and twistors: some exact results

TL;DR

This paper advances the understanding of D-instanton effects in string theory by providing exact, all-order results for hypermultiplet moduli spaces, extending previous linear approximations using twistor methods.

Contribution

It introduces a set of holomorphic functions capturing D-instanton effects at all orders and explicitly computes the hypermultiplet metric in specific charge sectors.

Findings

Holomorphic functions encode all-order D-instanton corrections.

Explicit hypermultiplet metric for sectors with vanishing symplectic invariant charges.

Extension beyond linear approximation in twistor-based instanton analysis.

Abstract

We present some results on instanton corrections to the hypermultiplet moduli space in Calabi-Yau compactifications of Type II string theories. Previously, using twistor methods, only a class of D-instantons (D2-instantons wrapping A-cycles) was incorporated exactly and the rest was treated only linearly. We go beyond the linear approximation and give a set of holomorphic functions which, through a known procedure, capture the effect of D-instantons at all orders. Moreover, we show that for a sector where all instanton charges have vanishing symplectic invariant scalar product, the hypermultiplet metric can be computed explicitly.