Fat Magnon

We consider a D-brane type state which shares the characteristic of the recently found giant magnon of Hofman and Maldacena. More specifically we find a bound state of giant graviton (D3-brane) and giant magnon (F-string), which has exactly the same anomalous dimension as that of the giant magnon. It is described by the D3-brane with electric flux which is topologically a $S^3$ elongated by the electric flux. The angular momentum and energy are infinite, but split sensibly into two parts -- the infinite part precisely the same as that of the giant magnon and the finite part which can be identified as the contribution from the giant graviton. We discuss that the corresponding dual gauge theory operator is not a simple chain type but rather admixture of the (sub-)determinant and chain types.Comment: 18 pages, 5 figures; v2 references added; v3 a reference added; v4 added a reference and discussions on the physical CFT operator. The version to appear in JHE

Models with Quartic Potential of Dynamical SUSY Breaking in Meta-Stable Vacua

We search for models of dynamical SUSY breaking in meta-stable vacua which might have dual string descriptions with a few brane probes. Two models with quartic superpotential are proposed: One of them might be closely related to the dual gauge theory to the flavored Maldacena-Nunez geometry by Casero, Nunez, and Paredes with a few additional brane probes corresponding to massive flavors. The other model might be dual to the Klebanov-Strassler geometry with one fractional D3-brane and a few D7-branes as probes.Comment: 16 pages; v2 added the reference hep-th/0608063 which is the first to have added a quartic potential stabilizing the would-be problematic modulu

Airy Function and 4d Quantum Gravity

We study four-dimensional quantum gravity with negative cosmological constant in the minisuperspace approximation and compute the partition function for the $S^3$ boundary geometry. In this approximation scheme the path integrals become dominated by a class of asymptotically AdS "microstate geometries." Despite the fact that the theory is pure Einstein gravity without supersymmetry, the result precisely reproduces, up to higher curvature corrections, the Airy function in the $S^3$ partition function of the maximally supersymmetric Chern-Simons-matter (CSM) theory which sums up all perturbative $1/N$ corrections. We also show that this can be interpreted as a concrete realization of the idea that the CFT partition function is a solution to the Wheeler-DeWitt equation as advocated in the holographic renormalization group. Furthermore, the agreement persists upon the inclusion of a string probe and it reproduces the Airy function in the vev of half-BPS Wilson loops in the CSM theory. These results may suggest that the supergravity path integrals localize to the minisuperspace in certain cases and the use of the minisuperspace approximation in AdS/CFT may be a viable approach to study $1/N$ corrections to large $N$ CFTs.Comment: 17 page

Branes Ending On Branes In A Tachyon Model

In a tachyon model proposed by Minahan and Zwiebach and derived in the boundary string field theory, we construct various new solutions which correspond to nontrivial brane configurations in string theory. Our solutions include Dp-D(p-2) bound states, (F, Dp) bound states, string junctions, D(p-2)-branes ending on a Dp-brane, D(p-2)-branes suspended between parallel Dp-branes and their non-commutative generalizations. We find the Bogomol'nyi bounds and the BPS equations for some of our solutions, and check the physical consistency of our solutions with the D-brane picture by looking at the distributions of their energies and RR-charges in space. We also give conjectures for a few other brane configurations.Comment: 19 pages, LaTeX, minor corrections and references adde

Topological Matrix Model

Starting from the primal principle based on the noncommutative nature of (9+1)-dimensional spacetime, we construct a topologically twisted version of the supersymmetric reduced model with a certain modification. Our formulation automatically provides extra 1+1 dimensions, thereby the dimensions of spacetime are promoted to 10+2. With a suitable gauge choice, we can reduce the model with (10+2)-dimensional spacetime to the one with (9+1)-dimensions and thus we regard this gauge as the light-cone gauge. It is suggested that the model so obtained would describe the light-cone F-theory. From this viewpoint we argue the relation of the reduced model to the matrix model of M-theory and the SL(2,Z) symmetry of type IIB string theory. We also discuss the general covariance of the matrix model in a broken phase, and make some comments on the background independence.Comment: 18 pages, LaTeX, no figures, minor corrections and modifications, references adde

Anomalous radius shift in AdS(4)/CFT(3)

We study higher order corrections to the radius/M2-brane charge of AdS_4 x S^7/Z_k. There are two sources of corrections: one from the orbifold singularity of C^4/Z_k, and the other from the discrete torsion associated with the homology 3-cycle H_3(S^7/Z_k,Z) = Z_k. We give a precise formula for the charge shift. These corrections are relevant, for example, at two loops in the AdS_4 x CP^3 sigma model, and therefore for the strong coupling test of the all loop Bethe ansatz.Comment: 16 pages; v2: The Type IIA D-brane probe calculation has been corrected, and now agrees with the M theory calculation. Appendix on conventions for RR fields and D-brane actions added. Note added on a possible correction due to a parity anomaly. References adde

Three dimensional Janus and time-dependent black holes

We show that the three dimensional Janus geometry can be embedded into the type IIB supergravity and discuss its dual CFT description. We also find exact solutions of time dependent black holes with a nontrivial dilaton field in three and higher dimensions as an application of the Janus construction.Comment: 17 pages, 1 figure; v2 minor corrections, references adde