118306090
Role of Tachyon in the Graceful Exit Problem
119401169
De Sitter vacua from N=2 gauged supergravity
Typical de Sitter (dS) vacua of gauged supergravity correspond to saddle points of the potential and often the unstable mode runs into a singularity. We explore the possibility to obtain dS points where the unstable mode goes on both sides into a supersymmetric smooth vacuum. Within N = 2 gauged supergravity coupled to the universal hypermultiplet, we have found a potential which has two supersymmetric minima (one of them can be flat) and these are connected by a de Sitter saddle point. In order to obtain this potential by an abelian gauging, it was important to include the recently proposed quantum corrections to the universal hypermultiplet sector. Our results apply to four as well as five dimensional gauged supergravity theories.
122300442
Perturbed superpotentials for coset models
Abstract A class of topological minimal matter corresponding to some of the coset models of Kazama and Suzuki is investigated. Starting from the general principle, the perturbed superpotentials for the corresponding models are explicitly constructed. These perturbed. superpotentials contain all the information about physical amplitudes in the topological theory.
15254278
D-instantons and Black Holes in N=2, D=4 Supergravity
We discuss T-duality between the solutions of type II A versus type II B superstrings compactiied on Calabi-Yau threefolds. Within the context of N = 2, D = 4 supergravity eeective Lagrangian, the T-duality transformation is equivalently described by the c-map, which transforms the IIA black hole solutions into the IIB D-instanton solutions. We construct via this mapping a broad class of D-instanton solutions in four dimensions.
99770174
Supersymmetric Configurations in Gauged Supergravity
We discuss supersymmetric configurations in gauged supergravity theories with particular emphasis on Euclidean D = 4, N = 4 gauged SU(2) × SU(1,1) supergravity.
17322810
Planetoid strings: Solutions and perturbations
A novel ansatz for solving the string equations of motion and constraints in generic curved backgrounds, namely the planetoid ansatz, was proposed recently by some authors. We construct several specific examples of planetoid strings in curved backgrounds which include Lorentzian wormholes, spherical Rindler spacetime and the (2 + 1)-dimensional black hole. A semiclassical quantization is performed and the Regge relations for the planetoids are obtained. The general equations for the study of small perturbations about these solutions are written down using the standard, covariant formalism. Applications to special cases such as those of planetoid strings in Minkowski and spherical Rindler spacetimes are also presented.
118116271
Directed Random Walks on Colored, Periodic Lattices: A Gauge Theoretic Approach
We define a random walk problem which admits analytic results, on a class of infinite periodic lattices which are directed and colored. Our approach is motivated from the fact that such lattices arise in string theoretic constructs of certain gauge theories. An operator counting problem in the latter is mapped to a problem in random walks. This is illustrated with several examples.
118521608
Black hole entropy corrections in the grand canonical ensemble
We study entropy corrections due to thermal fluctuations for asymptotically AdS black holes in the grand canonical ensemble. To leading order, these can be expressed in terms of the black hole response coefficients via fluctuation moments. We also analyze entropy corrections due to mass and charge fluctuations of R-charged black holes, and our results indicate an universality in the logarithmic corrections to charged AdS black hole entropy in various dimensions.