Transitive Courant Algebroids, String Structures and T-duality

Understand

In this paper, we use reduction by extended actions to give a construction of transitive Courant algebroids from string classes.

• We prove that T-duality commutes with the reductions and thereby determine global conditions for the existence of T-duals in heterotic string theory.
• In particular we find that T-duality exchanges string structures and gives an isomorphism of transitive Courant algebroids.
• Consequently we derive the T-duality transformation for generalised metrics and show that the heterotic Einstein equations are preserved.