Related papers: Towards open-closed string duality: Closed Strings…

In a recent paper we have proposed the possibility that the lightest massive string states could be identified with open strings living at intersections of D-branes forming small angles. In this note, we reconsider the relevant twist-field…

In this letter we present an operator formalism for Closed String Field Theory based on closed half-strings. Our results indicate that the restricted polyhedra of the classical non-polynomial string field theory, can be represented as…

We study the D-brane spectrum of N=2 string orbifold theories using the boundary state formalism. The construction is carried out for orbifolds with isolated singularities, non-isolated singularities and orbifolds with discrete torsion. Our…

This thesis is based on some selected topics in open topological string theory which I have worked on during my Ph.D. It comprises an introductory part where I have focused on the points most needed for the later chapters, trading…

This article, based on the Klein lecture, contains some new results and new speculations on various topics. They include discussion of open strings in the AdS space, unusual features of D-branes, conformal gauge theories in higher…

We suggest that the universe filled with unstable D-branes in their rolling tachyon vacuum state, described by periodic arrays of D-instantons along the imaginary time direction, may be a natural background for formulating string theory.…

We study covariant open bosonic string field theories on multiple $Dp$-branes by using the deformed cubic string field theory which is equivalent to the string field theory in the proper-time gauge. Constructing the Fock space…

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)…

In this review we describe our current understanding of the properties of open string tachyons on an unstable D-brane or brane-antibrane system in string theory. The various string theoretic methods used for this study include techniques of…

We construct solitonic states in the OSp invariant string field theory, which are BRST invariant in the leading order of regularization parameter. One can show that these solitonic states describe D-branes and ghost D-branes, by calculating…

Closed strings can be seen either as one-dimensional objects in a target space or as points in the free loop space. Correspondingly, a B-field can be seen either as a connection on a gerbe over the target space, or as a connection on a line…

In this Ph.D. thesis, we study some aspects of strings and branes. We mainly focus on anomalous D-brane couplings and on non-supersymmetric branes. In Chapter 2, we illustrate three key concepts in a field theory context: duality,…

The non-commutative geometry of a large auxiliary $B$-field simplifies the construction of D-branes as solitons in open string field theory. Similarly, fundamental strings are constructed as localized flux tubes in the string field theory.…

The description of D-branes as boundary states for type II string theories (in the covariant formulation) requires particular care in the R-R sector. Also the vertices for R-R potentials that can couple to D-branes need a careful handling.…

In addition to being a prime candidate for a fundamental unified theory of all interactions in nature, string theory provides a natural setting to understand gauge field theories. This is linked to the concept of "D-branes": extended,…

We study open and closed string interactions in the Type IIB plane wave background using open+closed string field theory. We reproduce all string amplitudes from the dual N=2 Sp(N) gauge theory by computing matrix elements of the dilatation…

We define a sequence of VSFT D-branes whose low energy limit leads exactly to a corresponding sequence of GMS solitons. The D-branes are defined by acting on a fixed VSFT lump with operators defined by means of Laguerre polynomials whose…

We show that the action expanded around Erler-Maccaferri's N D-brane solution describes the N+1 D-brane system where one D-brane disappears due to tachyon condensation. String fields on multi-branes can be regarded as block matrices of a…

We exhibit exact conformal field theory descriptions of SO(N) and Sp(N) pairs of Seiberg-dual gauge theories within string theory. The N=1 gauge theories with flavour are realized as low energy limits of the worldvolume theories on D-branes…

We here report a possibility of detecting the open string pair production from the system of a D3 brane, taken as our own (1 + 3)-dimensional world and carrying its worldvolume collinear electric and magnetic fluxes, and a nearby D-string,…