On Heterotic/Type I Duality in d=8

TL;DR

This paper investigates heterotic/type I duality in 8 dimensions by calculating string loop corrections and instanton effects, providing evidence for the duality through detailed threshold and R^2 correction analyses.

Contribution

It presents explicit calculations of gauge coupling corrections and instanton sums, advancing understanding of heterotic/type I duality in eight-dimensional string theories.

Findings

Confirmed duality through one-loop open string diagram calculations.

Derived D-instanton contributions matching heterotic corrections.

Computed threshold and R^2 corrections supporting duality consistency.

Abstract

We discuss heterotic corrections to quartic internal U(1) gauge couplings and check duality by calculating one-loop open string diagrams and identifying the D-instanton sum in the dual type I picture. We also compute SO(8)^4 threshold corrections and finally R^2 corrections in type I theory.