Duality of N=2 Heterotic -- Type I Compactifications in Four Dimensions

TL;DR

This paper explores the duality between type I and heterotic string theories in four dimensions, demonstrating agreement in key physical quantities through detailed analysis of compactifications and BPS spectra.

Contribution

It provides a detailed comparison of Kahler potentials, gauge thresholds, and higher derivative F-terms in dual models, emphasizing the role of BPS states in type I theory.

Findings

Kahler potentials and gauge thresholds match in the weak coupling limit.

Higher derivative F-terms are determined by BPS spectra.

Duality holds for models with arbitrary SU(16) Wilson lines.

Abstract

We discuss type I -- heterotic duality in four-dimensional models obtained as a Coulomb phase of the six-dimensional U(16) orientifold model compactified on T^2 with arbitrary SU(16) Wilson lines. We show that Kahler potentials, gauge threshold corrections and the infinite tower of higher derivative F-terms agree in the limit that corresponds to weak coupling, large T^2 heterotic compactifications. On the type I side, all these quantities are completely determined by the spectrum of N=2 BPS states that originate from D=6 massless superstring modes.