One-loop Effective Action in Open-string theory

TL;DR

The paper analyzes the one-loop effective action in Z_2-orbifold compactifications of type-I string theory, revealing finite threshold effects and discussing implications for Type-I and Heterotic superstring equivalence.

Contribution

It demonstrates that for non-abelian groups, threshold effects are ultraviolet finite and expressed by a six-dimensional field theory, advancing understanding of string dualities.

Findings

Threshold effects are ultraviolet finite.

Threshold effects are given by six-dimensional field theory expressions.

Implications for Type-I and Heterotic string theory equivalence.

Abstract

This is a summary of the analysis of the one-loop effective action in Z_2-orbifold compactifications of type-I theory presented in references [1,2]. We show how, for non-abelian group factors, the threshold effects are ultraviolet finite though given entirely by a six-dimensional field theory expression. We also discuss implications for the equivalence between Type-I and Heterotic four dimensional N=2 superstring theories.