Related papers: Worldsheet Formalism for Decoupling Limits in Stri…
We study a consistent deformation of the cubic open bosonic string theory in such a way that the non-planar world sheet diagrams of the perturbative string theory are mapped onto their equivalent planar diagrams of the light-cone string…
We review categorical aspects of 't Hooft's large $N$ expansion, which is expected to map any Quantum Field Theory of large matrices to a string theory. Our goal is to describe a general strategy to derive the string theory dual to given…
All bound states of fundamental strings, D-branes and NS-branes of string theory, both type-IIA and type-IIB, which may be described by a null geodesic motion on the coset G/K(G) where G is a group of type A, D or E embedded within E(11)…
The Romans type IIA supergravity allows fundamental strings to have explicit mass term at the tree level. We show that there exists a (F1,D2,D8) brane configuration which gives rise to $Lif_4^{(2)}\times {R}^1\times S^5$ vacua supported by…
We summarize recent progress in the understanding of minimal string theory, focusing on the worldsheet description of physical operators and D-branes. We review how a geometric interpretation of minimal string theory emerges naturally from…
The amplitudes in perturbative open string theory are examined as functions of the tachyon condensate parameter. The boundary state formalism demonstrates the decoupling of the open string modes at the non-perturbative minima of the tachyon…
In Type II string vacua constructed from intersecting/magnetized D-branes, the supersymmetry-breaking soft terms are genericaly non-universal. It is shown that universal supersymmetry-breaking soft terms may arise in a realistic MSSM…
We propose that type 0B string theory in two dimensions admits a dual description in terms of a one dimensional bosonic matrix model of a hermitian matrix. The potential in the matrix model is symmetric with respect to the parity-like Z_2…
We confront the problem of giving a fundamental definition to perturbative string theory in spacetimes with totally compact space (taken to be a torus for simplicity, though the nature of the problem is very general) and non-compact time.…
Despite impressive advances in the AdS3/CFT2 correspondence, the setup involving Ramond-Ramond backgrounds, which is related to the D1-D5 system of branes, remained relatively poorly understood. We use the Mirror TBA equations recently…
Four-dimensional compactifications of string theory provide a controlled set of possible gauge representations accounting for BSM particles and dark sector components. In this review, constraints from perturbative Type II string…
We study aspects of obtaining field theories with noncommuting time-space coordinates as limits of open-string theories in constant electric-field backgrounds. We find that, within the standard closed-string backgrounds, there is an…
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…
We argue for the existence of phase transitions in $3+1$ dimensions associated with the appearance of tensionless strings. The massless spectrum of this theory does not contain a graviton: it consists of one $N=2$ vector multiplet and one…
We study the self-duality of Born-Infeld-Chern-Simons theory which can be interpreted as a massive D2 brane in IIA string theory and exhibit the self-dual formulation in terms of the gauge invariant master Lagrangian. The proposed master…
I discuss D0-brane quantum mechanics as a nonperturbative formulation of string theory, in particular the relation between the Banks-Fischler-Shenker-Susskind matrix model, the Maldacena conjecture for D0-branes, and type IIA/M-theory…
A discrete string theory --a theory of embeddings from ${\bf Z}\times {\bf Z}_C\to {\bf R}^D$, where $C$ is the number of components of the string-- is explored. The closure of the algebra of constraints (`${\bf Z}_C$-Virasoro algebra') is…
D-branes intersecting at an arbitrary fixed angle generically constitute a configuration unstable toward recombination. The reconnection of the branes nucleates at the intersection point and involves a generalization of the process of brane…
In this paper we perform a detailed investigation of the Dirichlet eight-brane of the Type IIA string theory, when the effects of gravity are included. In particular, consider what happens when one allows the ten-form field strength…
We study various aspects of D-branes in the two families of closed N=2 strings denoted by \alpha and \beta in hep-th/0211147. We consider two types of N=2 boundary conditions, A-type and B-type. We analyse the D-branes geometry. We compute…