New type IIB vacua and their F-theory interpretation

We discuss a D3-D7 system in type IIB string theory. The near-horizon geometry is described by AdS5×X5 where X5 is a U(1) bundle over a Kähler-Einstein complex surface S with positive first Chern class c1>0. The surface S can either be P1×P1, P2 or Pn1,…,nk, a blow up of P2 at k points with 3≤k≤8. The P2 corresponds to the maximally supersymmetric AdS5×S5 vacuum while the other cases lead to vacua with less supersymmetries. In the F-theory context they can be viewed as compactifications on elliptically fibered almost Fano 3-folds.