On the strong coupling behavior of heterotic and type I orbifolds

TL;DR

This paper investigates the strong coupling behavior of heterotic and type I orbifolds, revealing their non-perturbative connections and deformations in string theory effective actions.

Contribution

It demonstrates how certain orbifolds of type IIB string theory relate to heterotic and type I models, highlighting non-perturbative effects on gauge groups.

Findings

Orbifolds connect heterotic and type I string theories.

Non-perturbative deformations affect gauge group structure.

Effective actions show consistent coupling behaviors.

Abstract

We study the bulk effective theory of a class of orbifolds of the type IIB string with D5-branes, compactified to four dimensions. These constructions are connected, in a region of their moduli space, to some orbifolds of the type I and heterotic string. We compare the effective actions through the coupling of the R^2 term, and we argue that these orbifolds provide non-perturbative deformations of the latter, in which the gauge group is entirely non-perturbative.