On the perturbative corrections around D-string instantons

TL;DR

This paper investigates perturbative corrections around D-string instantons in eight-dimensional string theories, demonstrating a precise agreement with fundamental string calculations and extending this correspondence to all orders.

Contribution

It provides a detailed analysis of ${ m F}^4$-threshold corrections and shows the all-order agreement between D-string instanton and fundamental string descriptions.

Findings

First subleading term matches exactly between D-string and fundamental string calculations.

Explicit calculation using Nambu-Goto action confirms the agreement.

The agreement between the two descriptions extends to all orders.

Abstract

We study ${\cal F}^4$-threshold corrections in an eight dimensional S-dual pair of string theories, as a prototype of dual string vacua with sixteen supercharges. We show that the orbifold CFT description of D-string instantons gives rise to a perturbative expansion similar to the one appearing on the fundamental string side. By an explicit calculation, using the Nambu-Goto action in the static gauge, we show that the first subleading term agrees precisely on the two sides. We then give a general argument to show that the agreement extends to all orders.