On Relativistic Brane Probes in Singular Spacetimes

We study the relativistic dynamics of brane probes in singular warped spacetimes and establish limits for such analysis. The behavior of the semiclassical brane probe wave functions implies that unitarity boundary conditions can be imposed at the singularity.Comment: 9 pages, 1 figure, typos corrected and references adde

Exponential Hierarchy From Spacetime Variable String Vacua

It is shown that non-supersymmetric spacetime varying string vacua can lead to an exponential hierarchy between the electroweak and the gravitational scales. The hierarchy is naturally generated by a string coupling of O(1).Comment: 22 pages, Latex, 2 figure

Probing Naked Singularities in Non-supersymmetric String Vacua

We present a detailed analysis of non-supersymmetric spacetime varying string vacua which can lead to an exponential hierarchy between the electroweak and the gravitational scales. In particular, we identify a limit in which these vacua can be interpreted as supersymmetric vacua of F-theory. Furthermore, we study the properties of these solutions as seen by $D7$-brane probes and establish a non-supersymmetric analogue of the enhancon mechanism.Comment: 46 pages, Latex, 7 figures; the brane probe analysis (sections 3 and 4) has been revised, references added and typos correcte

On the Geometry and Homology of Certain Simple Stratified Varieties

We study certain mild degenerations of algebraic varieties which appear in the analysis of a large class of supersymmetric theories, including superstring theory. We analyze Witten's sigma-model and find that the non-transversality of the superpotential induces a singularization and stratification of the ground state variety. This stratified variety (the union of the singular ground state variety and its exo-curve strata) admit homology groups which, excepting the middle dimension, satisfy the "Kahler package" of requirements, extend the "flopped" pair of small resolutions to an "(exo)flopped" triple, and is compatible with mirror symmetry and string theory. Finally, we revisit the conifold transition as it applies to our formalism.Comment: LaTeX 2e, 18 pages, 4 figure