Moduli instability in warped compactifications of the type-IIB supergravity

Abstract

We show that the conifold and deformed-conifold warped compactifications of the ten-dimensional type IIB supergravity, including the Klebanov-Strassler solution, are dynamically unstable in the moduli sector representing the scale of a Calabi-Yau space, although it can be practically stable for a quite long time in a region with a large warp factor. This instability is associated with complete supersymmetry breaking except for a special case and produces significant time-dependence in the structure of the four-dimensional base spacetime as well as of the internal space.

Dynamical D4-D8 and D3-D7 branes in supergravity

“…We found a class of time-dependent solutions for intersecting D4-D8-and D3-D7-brane systems. These solutions were obtained by replacing a constant A in the warp factor h = A + h 1 (y) of a supersymmetric solution by a function h 0 (x) of the coordinates x µ [21], where the coordinates y i would describe the internal space and x µ would describe our Universe. In the D4-D8 brane solution, the geometry was found to approach a warped static AdS 6 × S 4 in a certain region of the spacetime.…”

“…As seen from these equations, the internal space Y is not necessarily Ricci flat, and the function h 0 becomes more complicated. For example, when the metric q µν is Minkowski, h 0 is no longer linear in the coordinates x µ but quadratic in them [21].…”

Radion cosmology and stabilization

“…In particular, the Klebanov-Strassler throat geometry with a D 3 -D 7 brane configuration has a close resemblance with the warped geometry and can be stabilized by 3-form fluxes [46,47]. All geometric moduli can thus be classically stabilized by the field strengths of various form fields.…”

Dynamics of Intersecting Brane Systems

“…As a special example, we consider the case 27) where δ ij is the (D − p − 1)-dimensional Euclidean metric. In this case, the solution for H I can be obtained explicitly as…”