String-Unification, Universal One-Loop Corrections and Strongly Coupled Heterotic String Theory

TL;DR

This paper derives universal threshold corrections in heterotic string theory with Wilson lines, clarifies their role in gauge-gravity unification, and discusses potential extrapolation to strongly coupled heterotic string theory via M-theory.

Contribution

It provides the first derivation of universal one-loop threshold corrections including Wilson lines and explores their implications for unification and strong coupling extrapolation.

Findings

Universal threshold corrections are derived with Wilson lines.

Gauge and gravitational coupling unification is feasible within perturbative string theory.

Extrapolation to M-theory is plausible due to the holomorphic structure of gauge couplings.

Abstract

We derive the universal threshold corrections in heterotic string theory including a continuous Wilson line. Unification of gauge and gravitational couplings is shown to be possible even within perturbative string theory. The relative importance of gauge group dependent and independent thresholds on unification is clarified. Equipped with these results we can then attempt an extrapolation to the strongly coupled heterotic string -- M-theory. We argue that such an extrapolation might be meaningful because of the holomorphic structure of the gauge coupling function and the close connection of the threshold corrections to the anomaly cancelation mechanism.