Fermion Exchange between D-instantons

TL;DR

This paper investigates fermionic zero modes in type-IIB D-instantons, revealing that fermion exchange interactions are strongly attractive at short distances, impacting the instanton-anti-instanton dynamics and singularities.

Contribution

It introduces fermionic collective coordinates for D-instantons and derives fermion-exchange interactions from world-sheet Ward identities, highlighting their effects at short distances.

Findings

Fermionic zero modes follow clustering rules in the dilute gas limit.

Fermion exchange interactions are strongly attractive at string-scale distances.

Attractive fermion exchange enhances the short-distance Hagedorn singularity.

Abstract

We define fermionic collective coordinates for type-IIB Dirichlet instantons and discuss some effects of the associated fermionic zero modes within the dilute gas framework. We show that the standard rules for clustering of zero modes in the dilute limit, and the fermion-exchange interactions follow from world-sheet Ward identities. Fermion exchange is strongly attractive at string-scale distances, which makes the short-distance Hagedorn singularity between instantons and anti-instantons even stronger.