Non-supersymmetric infrared perturbations to the warped deformed conifold

We analyze properties of non-supersymmetric, isometry-preserving perturbations to the infrared region of the warped deformed conifold, i.e. the Klebanov-Strassler solution. We discuss both perturbations that "squash" the geometry, so that the internal space is no longer conformally Calabi-Yau, and perturbations that do not squash the geometry. Among the perturbations that we discuss is the solution that describes the linearized near-tip backreaction of a smeared collection of (D3) over bar -branes positioned in the deep infrared. Such a configuration is a candidate gravity dual of a non-supersymmetric state in a large-rank cascading gauge theory. Although (D3) over bar -branes do not directly couple to the 3-form flux, we argue that, due to the presence of the background imaginary self-dual flux, (D3) over bar -branes in the Klebanov-Strassler geometry necessarily produce singular non-imaginary self-dual flux. Moreover, since conformally Calabi-Yau geometries cannot be supported by non-imaginary self-dual flux, the (D3) over bar -branes squash the geometry as our explicit solution shows. We also briefly discuss supersymmetry-breaking perturbations at large radii and the effect of the non-supersymmetric perturbations on the gravitino mass. (C) 2010 Elsevier B.V. All rights reserved