High Energy Theory Seminar

I describe new perturbative compactifications of Type II string theory that rely on a fibration structure of the extra dimensions. Non-geometric spaces are obtained by enlarging the fiber monodromy group to include stringy duality symmetries. These vacua generically preserve N=1 supersymmetry in four dimensions, and are U-dual to M-theory on G2 manifolds. I also give an explanation for the Hanany-Witten brane-creation effect from this semiflat viewpoint.