Related papers: Linear Dilatons, NS5-branes and Holography
The weakly coupled vacuum of $E_8\otimes E_8$ heterotic string theory remains an attractive scenario for particle physics. The particle spectrum and the issue of dilaton stabilization are reviewed. A specific model for hidden sector…
In this paper we study string theory in the background $\mathcal{M}_3$ that interpolates between $AdS_3$ in the IR and linear dilaton spacetime $\mathbb{R}^{1,1}\times\mathbb{R}_\phi$ in the UV. Via holographic duality this background…
We analyze in detail the D-branes in the near-horizon limit of NS5-branes on a circle, the holographic dual of little string theory in a double scaling limit. We emphasize their geometry in the background of the NS5-branes and show the…
A brief review of the status of duality symmetries in string theory is presented. The evidence is accumulating rapidly that an enormous group of duality symmetries, including perturbative T dualities and non-perturbative S-dualities,…
This thesis focuses on the derivation of holographic backgrounds from the field theory side, without using any supergravity equations of motion. Instead, we rely on the addition of probe D-branes to the stack of D-branes generating the…
It is not understood whether scale-separated AdS vacua in string theory admit a holographic dual. A well-known class of such vacua is provided by the DGKT solutions of massive type IIA string theory, where scale separation arises from large…
We initiate a study of the holographic duals of a class of four-dimensional $\mathcal{N}=2$ superconformal field theories that are engineered by wrapping M5-branes on a sphere with an irregular puncture. These notably include the…
We examine the T-duality relation between 1+1 NCOS and the DLCQ limit of type IIA string theory. We show that, as long as there is a compact dimension, one can meaningfully define an `NCOS' limit of IIB/A string theory even in the absence…
String theory is the most promising candidate for the theory unifying all interactions including gravity. It has an extremely difficult dynamics. Therefore, it is useful to study some its simplifications. One of them is non-critical string…
In this paper we study the interplay of electric and magnetic backgrounds in determining the decoupling limit of coincident D-branes towards a noncommutative Yang-Mills (NCYM) or open string (NCOS) theory. No decoupling limit has been found…
This thesis follows two main lines of research, both related to relevant aspects of string theory and its phenomenological/cosmological applications. We study two different generalizations of the integrable SG model to NC geometry, after…
A naive dimensional reduction of the $N=1, D=10$ supergravity theory that naturally arises in five-brane models is used to determine the r\^ole of two fields which are basic ingredients of string models: the dilaton and, among the moduli,…
This dissertation consists of a comprehensive and pedagogical review of Maldacena's original derivation of the AdS/CFT correspondence and the main topics of string theory necessary to understand it. The large $N$ expansion of Yang-Mills…
In string theory it is known that abelian isometries in the sigma model lead to target space duality. We generalize this duality to backgrounds with non--abelian isometries. The procedure we follow consists of gauging the isometries of the…
We discuss string theory methods for the study of strongly coupled holographic defect conformal field theories (CFTs) which are dual to probe-brane systems. First, we examine whether the string theory duals of such defect CFTs are…
We study the correspondence between AdS$_3$ massive IIA supergravity vacua and two-dimensional $\mathcal{N}=(0,4)$ quiver quantum field theories. After categorizing all kinds of gravity solutions, we demystify the ones that seem to reflect…
We show that holography imposes strong and general constraints on scalar field potentials in the string landscape, determined by the asymptotic structure of the underlying spacetime. Applying these holographic consistency conditions, we…
We generalize the results of Polchinski and Strassler regarding the N=1-preserving mass deformation of N=4 SU(N) SYM theories and its string theory dual to SO(N) and USp(2N) gauge groups. The string theory duals involve 5-branes wrapped on…
This work investigates cosmic topological defects in gauge theories, focusing on models with an $SU(N)$ gauge group coupled with a single flavor, explored through a holographic framework. At low energies, the effective theory is described…
Quantization of closed string proceeds with a suitable choice of worldsheet vacuum. A priori, the vacuum may be chosen independently for left-moving and right-moving sectors. We construct {\sl ab initio} quantized bosonic string theory with…