Quantization of Dyon Charge and Electric-Magnetic Duality in String Theory

TL;DR

This paper investigates the spectrum of dyon charges in heterotic string theory, demonstrating its invariance under electric-magnetic duality, which supports the conjecture of this symmetry being exact in string theory.

Contribution

It provides a detailed analysis of dyon charge spectra in heterotic string theory and confirms duality invariance at arbitrary coupling and theta angles.

Findings

Dyon charge spectrum is invariant under duality transformations.

Supports the conjecture that electric-magnetic duality is an exact symmetry in string theory.

Analysis applies at arbitrary string coupling and theta angle values.

Abstract

We analyze the allowed spectrum of electric and magnetic charges carried by dyons in (toroidally compactified) heterotic string theory in four dimensions at arbitrary values of the string coupling constant and $\theta$ angle. The spectrum is shown to be invariant under electric-magnetic duality transformation, thereby providing support to the conjecture that this is an exact symmetry in string theory.