Double Field Theory Formulation of Heterotic Strings

TL;DR

This paper extends double field theory to heterotic strings, incorporating gauge vectors and symmetries, providing a unified covariant framework for both abelian and non-abelian sectors.

Contribution

It introduces a generalized metric and covariant constraints for heterotic strings within double field theory, unifying abelian and non-abelian gauge sectors.

Findings

Unified O(D,D+n) covariant formulation for heterotic strings

Structural similarity between abelian and bosonic string actions

Covariant action for non-abelian gauge couplings

Abstract

We extend the recently constructed double field theory formulation of the low-energy theory of the closed bosonic string to the heterotic string. The action can be written in terms of a generalized metric that is a covariant tensor under O(D,D+n), where n denotes the number of gauge vectors, and n additional coordinates are introduced together with a covariant constraint that locally removes these new coordinates. For the abelian subsector, the action takes the same structural form as for the bosonic string, but based on the enlarged generalized metric, thereby featuring a global O(D,D+n) symmetry. After turning on non-abelian gauge couplings, this global symmetry is broken, but the action can still be written in a fully O(D,D+n) covariant fashion, in analogy to similar constructions in gauged supergravities.