Related papers: Dilaton, moduli and string/five-brane duality as s…
A recent attempt to extend the geometric Langlands duality to affine Kac-Moody groups, has led Braverman and Finkelberg [arXiv:0711.2083] to conjecture a mathematical relation between the intersection cohomology of the moduli space of…
The heterotic string theory, compactified to four dimensions, has been conjectured to have a duality symmetry (S duality) that transforms the dilaton nonlinearly. If valid, this symmetry could provide an important means of obtaining…
We study a three-dimensional gauge theory obtained from the dimensional reduction of a D4-brane worldvolume theory in the background of space-time moduli. An SL(3) symmetry in this theory, which acts on fields as well as coupling constants,…
These lectures begin by reviewing the evidence for S duality of the toroidally compactified heterotic string in 4d that was obtained in the period 1992--94. Next they review recently discovered dualities that relate all five of the 10d…
The SL(2,Z) anomaly recently derived for type IIB supergravity in 10 dimensions is shown to be a consequence of T-duality with the type IIA string, after compactification to 2 dimensions on an 8-fold. This explains the identity of the…
All the models of elementary particles and their interactions derived from String Theory involve a compact six-dimensional internal space. Its volume and shape should be fixed or stabilized, since otherwise massless scalar fields (moduli)…
We consider N=1 dualities in four dimensional supersymmetric gauge theories as a geometrical realization of wrapping D 6-branes around 3-cycles of Calabi-Yau threefolds in type IIA string theory. By extending the recent work of Ooguri and…
String duality suggests a fascinating juxtoposition of world-volume and target-space dynamics. This is particularly apparent in the $D$-brane description of stringy solitons that forms a major focus of this article (which is {\it not}…
In this work we present the minimal supersymmetric extension of the five-dimensional dilaton-gravity theory that captures the main properties of the holographic dual of little string theory. It is described by a particular gauging of…
The strong coupling dynamics of string theories in dimension $d\geq 4$ are studied. It is argued, among other things, that eleven-dimensional supergravity arises as a low energy limit of the ten-dimensional Type IIA superstring, and that a…
String theory requires two kinds of loop expansion: classical $(\alpha')$ worldsheet loops with expansion parameter $<T>$ where $T$ is a modulus field, and quantum $(\hbar)$ spacetime loops with expansion parameter $<S>$ where $S$ is the…
Modifications to the singularity structure of D3-branes that result from turning on a flux for the R-R and NS-NS 3-forms (fractional D3-branes) provide important gravity duals of four-dimensional N=1 super-Yang-Mills theories. We construct…
Four dimensional supergravities may be the right framework to describe particle physics at low energies. Its connection to the underlying string theory can be implemented through higher dimensional supergravities which bear special…
We consider a scalar field interaction with a cosmic string configuration in a flat 3-brane. The origin of this field is given by a compactification mechanism in the context of a 5-dimensional Brans-Dicke theory. We use the Cosmic Microwave…
We examine $(D-2)$-brane solutions in supergravities, showing that they fall into four categories depending on the details of the dilaton coupling. In general they describe domain walls, although in one of the four categories the metric…
In the context of brane gas cosmology in superstring theory, we show why it is impossible to simultaneously stabilize the dilaton and the radion with a general gas of strings (including massless modes) and D-branes. Although this requires…
We discuss various dual {\it pairs} of $M$-theory compactifications. Each pair consists of a compactification in which the two-brane plays the crucial role in relation to a string theory and a compactification in which the five-brane takes…
We analyze the process of string vacuum destabilization due to instanton induced superpotential couplings which depend linearly on charged fields. These non-perturbative instabilities result in potentials for the D-brane moduli and lead to…
After simultaneous compactification of spacetime and worldvolume on $K3$, the $D=10$ heterotic fivebrane with gauge group $SO(32)$ behaves like a $D=6$ heterotic string with gauge group $SO(28) \times SU(2)$, but with Kac--Moody levels…
We consider a compactification with a six-dimensional torus in the type II brane gas models. We show that the dilaton and the scale of each cycle of the internal space are fixed in the presence of NS5-brane and Kaluza-Klein monopoles as…