Related papers: Closed string exchanges on $C^2/Z_2$ in a backgrou…

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…

This paper addresses several unsettled issues associated with string creation in systems of orthogonal Dp-D(8-p) branes. The interaction between the branes can be understood either from the closed string or open string picture. In the…

A non-supersymmetric ten-dimensional open string theory is constructed as an orbifold of type I string theory, and as an orientifold of the bosonic type B theory. It is purely bosonic, and cancellation of massless tadpoles requires the…

We use the remodeling approach to the B-model topological string in terms of recursion relations to study open string amplitudes at orbifold points. To this end, we clarify modular properties of the open amplitudes and rewrite them in a…

We present brane constructions in Type IIA string theory for N=1 supersymmetric SO and Sp gauge theories with tensor representations using an orientifold 6-plane. One limit of these set-ups corresponds to N=2 theories previously constructed…

We investigate the interactions of closed strings in IIB matrix model. The basic interaction of the closed superstring is realized by the recombination of two intersecting strings. Such interaction is investigated in IIB matrix model via…

We evaluate the string theory disc amplitude of one Ramond-Ramond field C^(p-3) and two Neveu-Schwarz B-fields in the presence of a single Dp-brane in type II string theory. From this amplitude we extract the four-derivative (or…

Refining previous work by Iso, Kawai and Kitazawa, we discuss bi-local string states as a tool for loop computations in noncommutative field theory and matrix models. Defined in terms of coherent states, they exhibit the stringy features of…

An interesting consequence of string dualities is that they reveal situations where the geometry of a string background appears to be globally ill-defined, a phenomenon usually referred to as non-geometry. On the other hand, string theory…

We use semiclassical method to study closed strings in the modified AdS_5*S^5 background with constant B-fields. The point-like closed strings and the streched closed strings rotating around the big circle of S^5 are considered.…

It is an old speculation that SU(N) gauge theory can alternatively be formulated as a string theory. Recently this subject has been revived, in the wake of the discovery of D-branes. In particular, it has been argued that at least some…

We study effective quiver gauge theories arising from a stack of D3-branes on certain Calabi-Yau singularities. Our point of view is a first principle approach via open topological string theory. This means that we construct the natural…

This is the second paper of a series of three. We construct effective open-closed superstring couplings by classically integrating out massive fields from open superstring field theories coupled to an elementary gauge invariant tadpole…

Old fashioned duality used to derive the closed string field theory for magnetic vortex from the gauge theory with Higgs scalar, is applied to the string theories. The bosonic sring theory coupled to the Kalb-Ramond 2-form field is dually…

The nilpotent BRST, anti-BRST, dual-BRST and anti-dual-BRST symmetry transformations are constructed in the context of noncommutative (NC) 1-form as well as 2-form gauge theories. The corresponding Noether's charges for these symmetries on…

We extend an earlier proposal for a gauge invariant description of off-shell open strings (at tree level), using loop variables, to off-shell closed strings (at tree level). The basic idea is to describe the closed string amplitudes as a…

We use dyonic brane configurations of type 0 string theory to study large N non-supersymmetric 4d gauge theories. The brane configurations define theories similar to the supersymmetric ones which arise in type II. We find the non-SUSY…

In this paper we make an SL(2,Z)-covariant generalisation of the noncommutative theories, NCYM and NCOS on the D3-brane, and NCOS on the D5-brane in type IIB. Usually, the noncommutative theories are obtained by studying perturbative…

We propose a nonperturbative framework for the O(32) type I open and closed string theory. The short distance degrees of freedom are bosonic and fermionic hermitian matrices belonging respectively to the adjoint and fundamental…

We use rotation of one D-brane with respect to the other to reveal the hidden structure of D-branes in type-II theories. This is done by calculation of the interaction amplitude for two different parallel and angled branes. The analysis of…