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.
14708832
TARGET SPACE INTERPRETATION OF NEW MODULI IN 2D STRING THEORY
We analyze the new states that have recently been discovered in 2D string theory by E. Witten and B. Zwiebach. Since the Liouville direction is uncompactified, we show that the deformations by the new ghost number two states generate equivalent classical solutions of the string fields. We argue that the new ghost number one states are responsible for generating transformations which relate such equivalent solutions. We also discuss the possible interpretation of higher ghost number states of these.
14574084
FROM TYPE IIA BLACK HOLES TO T-DUAL TYPE IIB D-INSTANTONS IN N = 2, D = 4 SUPERGRAVITY
We discuss the T-duality between the solutions of type 11A versus IIB superstrings compactified on Calabi-Yau threefolds. Within the context of the N = 2, D = 4 supergravity effective Lagrangian, the T-duality transformation is equivalently described by the c-map, which relates the special Kahler moduli space of the IIA N = 2 vector multiplets to the quaternionic moduli space of the N = 2 hyper multiplets on the type IIB side (and vice versa). Hence the T-duality, or c-map respectively, transforms the IIA black hole solutions, originating from even-dimensional IIA branes, of the special Kahler effective action, into IIB D-instanton solutions of the IIB quaternionic σ-model action, where the D-instantons can be obtained by compactifying odd 1113 D-branes on the internal Calabi-Yau space. We construct via this mapping a broad class of D-instanton solutions in four dimensions which are determined by a set of harmonic functions plus the underlying topological Calabi-Yau data.
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.
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.