Related papers: Lectures on Non-BPS Dirichlet branes
A brief introduction to the boundary state approach to Dirichlet branes is given. The example of the non-BPS D-string of Type IIA on K3 is analysed in some detail, and its dual heterotic state is identified.
The relation between some perturbative non-BPS states of the heterotic theory on T^4 and non-perturbative non-BPS states of the orbifold limit of type IIA on K3 is exhibited. The relevant states include a non-BPS D-string, and a non-BPS…
We review the recent developments in our understanding of non-BPS states and branes in string theory. The topics include 1) construction of unstable non-BPS D-branes in type IIA and type IIB string theories, 2) construction of stable…
We give a detailed (microscopic) description of the geometric and non-geometric fundamental branes and their bound states in Type II superstring compactifications preserving N=6 supersymmetry. We consider general boundary states that couple…
There are two families of non-BPS bi-spinors in the perturbative spectrum of the nine dimensional heterotic string charged under the gauge group $SO(16)\times SO(16)$. The relation between these perturbative non-BPS states and certain…
In this article, applying different types of boundary conditions; Dirichlet, Neumann, or Mixed, on open strings we realize various new brane bound states in string theory. Calculating their interactions with other D-branes, we find their…
In these lectures we review the properties of a boosted and rotated boundary state and of a boundary state with an abelian gauge field deriving from it the Dirac-Born-Infeld action and a newly constructed class of classical solutions. We…
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,…
We study nonperturbative aspects of asymmetric orbifolds of type IIA, focussing on models that allow a dual perturbative heterotic description. In particular we derive the boundary states that describe the nonsupersymmetric D-branes of the…
For the bosonic string on the torus we compute boundary states describing branes with not trivial homology class in presence of constant closed and open background. It turns out that boundary states with non trivial open background…
We review the boundary state description of D-branes in type I string theory and show that the only stable non-BPS configurations are the D-particle and the D-instanton. We also compute the gauge and gravitational interactions of the…
We analyse the spectrum of non-BPS branes in the type I theory on the orbifold $T^4/{\cal I}_4$. We present a detailed analysis of the action of the worldsheet parity $\Omega$ on the different D-brane boundary state sectors of type IIB on…
Considering SO(32) heterotic string theory compactified on a torus of dimension 4 and less, stability of non-supersymmetric states is studied. A non-supersymmetric state with robust stability is constructed, and its exact stability is…
We describe a tachyon-free stable non-BPS brane configuration in type IIA string theory. The configuration is an elliptic model involving rotated NS5 branes, D4 branes and anti-D4 branes, and is dual to a fractional brane-antibrane pair…
In the previous paper [hep-th/9904129], we constructed a general explicit BPS solution for (F, D3) non-threshold bound state. By using the SL(2,Z) symmetry of type IIB string theory, we here construct from (F, D3) a more general BPS…
We work out boundary states for Type IIA string theory on a plane wave background. By directly utilizing the channel duality, the induced conditions from the open string boundary conditions are imposed on the boundary states. The resulting…
A detailed understanding of instanton effects for half-BPS couplings is pursued in theories with 16 supersymmetries. In particular, we investigate the duality between heterotic string on $T^4$ and type IIA on $K_3$ at the $T^4/Z_2$ orbifold…
We review the boundary state description of the non-BPS D-branes in the type I string theory and show that the only stable configurations are the D-particle and the D-instanton. We also compute the gauge and gravitational interactions of…
Spectrum of elementary string states in type II string theory compactified on a torus contains short multiplets which are invariant under only one quarter of the space-time supersymmetry generators. $U$-duality transformation converts these…
Polchinski's recent construction of Dirichlet-branes of R-R charges, together with Witten's mechanism for forming bound states of both NS-NS charges and R-R charges, provides a rigorous method to treat these dy-branes. We construct the…