Moduli stabilization in type IIB orientifolds (II)

We discuss general properties of moduli stabilization in KKLT scenarios in type IIB orientifold compactifications X6. In particular, we find conditions for the Kahler potential to allow a KKLT scenario for a manifold X6 without complex structure moduli, i.e. h(2,1)(-)(X6)=0. This way, a whole class of type IIB orientifolds with h(2,1)(-)(X6)=0 is ruled out. This excludes in particular all ZN- and ZNxZM-orientifolds X6 with h(2,1)(X6)=0 for a KKLT scenario. This concerns Z3, Z7, Z3xZ3, Z4xZ4, Z6xZ6 and Z2xZ6'-both at the orbifold point and away from it. Furthermore, we propose a mechanism to stabilize the Kahler moduli associated to the odd cohomology H-(1,1)(X6). In the second part of this work we discuss the moduli stabilization of resolved type IIB ZN- or ZNxZM-orbifold/orientifold compactifications. As examples for the resolved Z6 and Z2xZ4 orbifolds we fix all moduli through a combination of fluxes and racetrack superpotential