N=4 Gauged Supergravity from Duality-Twist Compactifications of String Theory

Understand

We investigate the lifting of half-maximal four-dimensional gauged supergravities to compactifications of string theory.

• It is shown that a class of such supergravities can arise from compactifications of IIA string theory on manifolds of SU(2)-structure which may be thought of as K3 fibrations over T^2.
• Examples of these SU(2)-structure backgrounds, as smooth K3 bundles and as compactifications with H-flux, are given and we also find evidence for a class of non-geometric, Mirror-fold backgrounds.
• By applying the duality between IIA string theory on K3 and Heterotic string theory on T^4 fibrewise, we argue that these SU(2)-structure backgrounds are dual to Heterotic compactifications on a class T^4 fibrations over T^2.