Related papers: On Unification of RR Couplings
I give an overview of open, closed and heterotic N=2 strings. At the tree level I derive the effective field theories of all the strings, and discuss the group theory of the N=2 open string and the interaction between its open and closed…
In one variable, there exists a satisfactory classification of commutative rings of differential operators. In several variables, even the simplest generalizations seem to be unknown and in this report we give examples and pose questions…
At first, we derive a boundary state, associated with a moving D$p$-brane, in the presence of the Kalb-Ramond field and a $U(1)$ gauge potential. Then, from the interaction of such D$p$-branes, we obtain the radiation amplitude for a…
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…
We study the notion of non-commumative higher dimensional local fields. A simplest example is the ring P of formal pseudo- differential operators. As an application we extend the KP hierarchy to the space $P^n$.
In the framework of a recently proposed method for computing exactly string amplitudes regularized in the infra-red, I determine the one-loop correlators for auxiliary fields in the symmetric $Z_2\times Z_2$ orbifold model. The $D$-field…
We reformulate bosonic boundary string field theory in terms of boundary state. In our formulation, we can formally perform the integration of target space equations of motion for arbitrary field configurations without assuming decoupling…
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…
In string theory the coupling parameters are functions of moduli fields. The actual values of the coupling constants are then dynamically determined through the vacuum expextation values of these fields. We review the attempts to connect…
We define several versions of the cohomology ring of an associative algebra. These ring structures unify some well known operations from homological algebra and differential geometry. They have some formal resemblance with the quantum…
KLT relations almost factorize closed string amplitudes on $S_2$ by two open string tree amplitudes which correspond to the left- and the right- moving sectors. In this paper, we investigate string amplitudes on $D_2$ and $RP_2$. We find…
We study closed string exchanges in background $B$-field. By analysing the two point one loop amplitude in bosonic string theory, we show that tree-level exchange of lowest lying, tachyonic and massless closed string modes, have IR…
We discuss T-duality for open strings in general background fields both in the functional integral formulation as well as in the language of canonical transformations. The Dirichlet boundary condition in the dual theory has to be treated as…
Closed string field theory leads to a generalization of Lie algebra which arose naturally within mathematics in the study of deformations of algebraic structures. It also appeared in work on higher spin particles \cite{BBvD}. Representation…
We compute higher-point superstring correlators involving spin fields in various even space-time dimensions D at tree-level and to arbitrary loop order. This generalizes previous work in D=4 space-time dimensions. The main focus are D=6,8…
We compute the left-right entanglement entropy for Dp-branes in string theory. We employ the CFT approach to string theory Dp-branes, in particular, its presentation as coherent states of the closed string sector. The entanglement entropy…
The connection between Riemann surfaces with boundaries and the theory of vertex operator algebras is discussed in the framework of conformal field theories defined by Kontsevich and Segal and in the framework of their generalizations in…
We extend to non-orientable surfaces previous work on sewing constraints in Conformal Field Theory. A new constraint, related to the real projective plane, is described and is used to illustrate the correspondence with a previous…
In hep-th/0211011 we started a systematic investigation of open strings in the plane wave background. In this paper we continue the analysis by discussing the superalgebras of conserved charges, the spectra of open strings, and the spectra…
The set of string vertices is extended to include moduli spaces with genus and numbers of ordinary and special punctures ranging over all integral values $g,n,\bar n\geq0$. It is argued that both the string background and the B-V delta…