Heterotic Effective Action and Duality Symmetries Revisited

TL;DR

This paper investigates the duality symmetries of heterotic supergravity, revealing a universal O(d,d;R) symmetry at all orders in α' and providing a new formulation using O(d,d) multiplets.

Contribution

It demonstrates the presence of a universal O(d,d;R) symmetry in heterotic effective actions, extending previous results and offering a novel O(d,d) multiplet formulation.

Findings

Universal O(d,d;R) symmetry confirmed at all α' orders.

New O(d,d) multiplet formulation of reduced supergravity.

Discussion of symmetry enhancement cases.

Abstract

The dimensional reduction of heterotic supergravity with gauge fields truncated to the Cartan subalgebra exhibits a continuous O(d,d+16;R) global symmetry, related to the O(d,d+16;Z) T-duality of heterotic strings on a d-torus. The O(d,d+16;R) symmetry is not present, however, if the supergravity reduction is done including the full set of E_8 x E_8 or SO(32) gauge fields. We analyze which duality symmetries are realized to all orders in $\alpha'$ in the proper effective field theories for the massless string states. We find a universal O(d,d;R) symmetry, also predicted by double field theory. We confirm this by giving a novel formulation of the dimensionally reduced supergravity in terms of O(d,d) multiplets, and we discuss cases of symmetry enhancement.