Related papers: Open-Closed Duality at Tree Level

In this note we present an explicit procedure for the regularization of tree level amplitudes involving discrete states, using open string field theory. We show that there is a natural correspondence between the discrete states and…

This is a series of remedial lectures on open and unoriented strings for the heterotic string generation. The particular focus is on the interesting features that arise under T-duality---D-branes and orientifolds. The final lecture…

What is the meaning of entanglement in a theory of extended objects such as strings? To address this question we consider the spatial entanglement between two intervals in the Gross-Taylor model, the string theory dual to two-dimensional…

We address the conjecture that at the tachyonic vacuum open strings get transformed into closed strings. We show that it is possible in the context of boundary string field theory to interpolate between the conventional open string theory,…

We discuss how to describe time-dependent phenomena in string theory like the decay of unstable D-branes with the help of the world-sheet formulation. It is shown in a nontrivial well-controlled example that the coupling of the tachyons to…

This thesis investigates correspondences between open and closed strings. This is done on the level of coupled open-closed moduli spaces and from a string field theoretic point of view. The construction of boundary string field theory on…

Following on from arXiv:1805.03657, we consider open strings in the non-Abelian T-dual of the $SU(2)_k$ WZW model, with respect to the vector $SU(2)$ isometry. Since in this case the dual theory has an exact CFT description, we look at the…

Two different mechanisms exist in non-perturbative String / M- theory for enhanced SU(N) (SO(2N)) gauge symmetries. It can appear in type IIA string theory or M-theory near an $A_{N-1}$ (D_N) type singularity where membrnes wrapped around…

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…

We discuss D-branes from a conformal field theory point of view. In this approach, branes are described by boundary states providing sources for closed string modes, independently of classical notions. The boundary states must satisfy…

We discuss graded D-brane systems of the topological A model on a Calabi-Yau threefold, by means of their string field theory. We give a detailed analysis of the extended string field action, showing that it satisfies the classical master…

Certain configurations of D-branes, for example wrong dimensional branes or the brane-antibrane system, are unstable to decay. This instability is described by the appearance of a tachyonic mode in the spectrum of open strings ending on the…

We study conformal field theory correlation functions relevant for string diagrams with open strings that stretch between several parallel branes of different dimensions. In the framework of conformal field theory, they involve boundary…

There is evidence that string theory possesses a large discretuum of stable and/or metastable ground states, with zero or four supersymmetries in four dimensions. I discuss critically the nature of this evidence. Assuming this "landscape"…

The spectrum of open strings on various non-BPS D-brane configurations in type II string theory on a K3 orbifold is analysed. At a generic point in the corresponding moduli space the spectrum of open strings does not have any degeneracy…

Closed string field theory is constructed by stochastically quantizing a matrix model for Polyakov loops that describes phases of a large N gauge theory at finite temperature. Coherent states in this string field theory describes winding…

Intersecting D6-branes provide a geometrically intuitive road to stringy particle physics models, where D6-branes stuck at orbifold singularities can lead to the stabilisation of deformation moduli, and the QCD axion can arise from the open…

We discuss the role played by the divergences appearing in the interaction between a fractional D3 brane dressed with an SU(N) gauge field and a stack of N fractional D3 branes on the orbifolds C^2/Z_2 and C^3/(Z_2 x Z_2). In particular we…

We analyse open strings with background electric fields in the internal space, T-dual to branes moving with constant velocities in the internal space. We find that the direction of the electric fields inside a two torus, dual to the D brane…

We consider Hull's doubled formalism for open strings on D-branes in flat space and construct the corresponding effective double field theory. We show that the worldsheet boundary conditions of the doubled formalism describe in a unified…