Stringy Instantons in IIB Brane Systems

TL;DR

This paper investigates rigid stringy D-brane instantons in type IIB Calabi-Yau compactifications, showing their superpotential contributions can be computed via a topological B-model using A-infinity structures.

Contribution

It introduces a topological B-model approach to calculate superpotential contributions from stringy instantons, providing a simple formula and focusing on non-Yang-Mills instantons.

Findings

Superpotential contributions are determined by a topological B-model computation.

The computation is governed by an A-infinity algebra structure.

A simple formula summarizes the instanton effects.

Abstract

In this note, we study D-brane instantons which intersect N=1 supersymmetric configurations of space-filling D-branes in general Calabi-Yau compactifications of type IIB string theory. Our focus is on rigid ``stringy instantons'' -- those which cannot be interpreted as Yang-Mills instantons in a non-Abelian gauge group on any stack of space-filling D-branes. We show that their contributions to the space-time superpotential can be determined by a topological B-model computation of the tree-level superpotential for a related auxiliary brane system. This computation is very tractable, as it is governed by an A-infinity structure. We summarize the stringy instanton contribution to the space-time superpotential in a simple formula.