Evidence for Heterotic/Heterotic Duality

TL;DR

This paper investigates a self-duality in heterotic string theory compactified on K3, revealing a symmetry that exchanges perturbative and non-perturbative gauge fields and inverts the coupling, with insights from eleven-dimensional M-theory.

Contribution

It demonstrates a self-duality of the $E_8 imes E_8$ heterotic string on K3 with equal instanton numbers, connecting perturbative and non-perturbative aspects via M-theory.

Findings

Identifies a self-duality that inverts the coupling and exchanges gauge fields.

Shows the special role of symmetric embedding in anomaly cancellation.

Uses M-theory compactification to derive the duality.

Abstract

We re-examine the question of heterotic - heterotic string duality in six dimensions and argue that the $E_8\times E_8$ heterotic string, compactified on $K3$ with equal instanton numbers in the two $E_8$'s, has a self-duality that inverts the coupling, dualizes the antisymmetric tensor, acts non-trivially on the hypermultiplets, and exchanges gauge fields that can be seen in perturbation theory with gauge fields of a non-perturbative origin. The special role of the symmetric embedding of the anomaly in the two $E_8$'s can be seen from field theory considerations or from an eleven-dimensional point of view. The duality can be deduced by looking in two different ways at eleven-dimensional $M$-theory compactified on $K3\times {\bf S}^1/\Z_2$.