Generalised geometry for string corrections

Understand

We present a general formalism for incorporating the string corrections in generalised geometry, which necessitates the extension of the generalised tangent bundle.

• Not only are such extensions obstructed, string symmetries and the existence of a well-defined effective action require a precise choice of the (generalised) connection.
• The action takes a universal form given by a generalised Lichnerowitz--Bismut theorem.
• As examples of this construction we discuss the corrections linear in $\alpha'$ in heterotic strings and the absence of such corrections for type II theories.