We study the mediation of supersymmetry breaking in string compactifications
whose moduli are stabilized by nonperturbative effects. We begin with a
critical review of arguments for sequestering in supergravity and in string
theory. We then show that geometric isolation, even in a highly warped space,
is insufficient to achieve sequestering: in type IIB compactifications,
nonperturbative superpotentials involving the Kahler moduli introduce
cross-couplings between well-separated visible and hidden sectors. The scale of
the resulting soft terms depends on the moduli stabilization scenario. In the
Large Volume Scenario, nonperturbative superpotential contributions to the soft
trilinear A terms can introduce significant flavor violation, while in KKLT
compactifications their effects are negligible. In both cases, the
contributions to the μ and Bμ parameters cannot be ignored in general.
We conclude that sequestered supersymmetry breaking is possible in
nonperturbatively-stabilized compactifications only if a mechanism in addition
to bulk locality suppresses superpotential cross-couplings.Comment: 47 page