Related papers: Type I Superstrings without D-branes

We determine the spectrum of D-string bound states in various classes of generalized type I vacuum configurations with sixteen and eight supercharges. The precise matching of the BPS spectra confirms the duality between unconventional type…

The study of curved D-brane geometries in type II strings implies a general relation between local singularities $\cx W$ of Calabi-Yau manifolds and gravity free supersymmetric QFT's. The minimal supersymmetric case is described by F-theory…

We construct six- and four-dimensional toroidal compactifications of the Type I string with magnetic flux on the D-branes. The open strings in this background probe a noncommutative internal geometry. Phenomenologically appealing features…

We study N=1 dualities in four dimensional supersymmetric gauge theories in terms of wrapping D 6-branes around 3-cycles of Calabi-Yau threefolds in type IIA string theory. We generalize the recent work of geometrical realization for the…

We study a class of type I string models with supersymmetry broken on the world-volume of some D-branes and vanishing tree-level potential. Despite the non-supersymmetric spectrum, supersymmetry is non-linearly realized on these D-branes,…

Intersecting D-brane worlds provide phenomenologically appealing constructions of four dimensional low energy string vacua. In this talk, a Z_4 x Z_2 orbifold background is taken into account. It is possible to obtain supersymmetric and…

We construct N=1 supersymmetric four-dimensional orientifolds of type IIA on T^6/(Z_2 x Z_2) with D6-branes intersecting at angles. The use of D6-branes not fully aligned with the O6-planes in the model allows for a construction of many…

We revisit the construction of the $\mathcal{N}=1$ supersymmetric trinification models with gauge group $\mathrm{U}(3)_C\times \mathrm{U}(3)_L \times \mathrm{U}(3)_R$ in Type IIA string theory on $\mathbf{T^6/(\mathbb{Z}_2\times…

We consider Z2, freely acting orbifolds of the type IIB string with 16 parallel D5-branes. When the string is compactified on T2 X T4 and the D5-branes are wrapped on T2, these systems possess N=2 supersymmetry, originating from the…

Several aspects concerning the physics of D-branes in Type II flux compactifications preserving minimal N=1 supersymmetry in four dimensions are considered. It is shown how these vacua are completely characterized in terms of properly…

Using a six-orientifold on top of a NS-fivebrane we construct a chiral N=1 supersymmetric gauge theory in four dimensions with gauge group SU(N_c) and matter in the symmetric, antisymmetric and (anti)fundamental representations. Anomaly…

We review the construction of chiral four-dimensional compactifications of type IIA string theory with intersecting D6-branes. Such models lead to four-dimensional theories with non-abelian gauge interactions and charged chiral fermions. We…

The state of the art in D-brane model building is briefly reviewed, focusing on recent achievements in the construction of D=4 N = 1 type II string vacua with semi-realistic gauge sectors. Such progress relies on a better understanding of…

We study Type I string theory compactified on a T^6/Z_3 orientifold. The low-energy dynamics is most conveniently analyzed in terms of D3-branes. We show that a sector of the theory, which corresponds to placing an odd number of D3-branes…

We construct open descendants of Gepner models, concentrating mainly on the six-dimensional case, where they give type I vacua with rich patterns of Chan-Paton symmetry breaking and various numbers of tensor multiplets, including zero. We…

We consider the propagation of Type I open superstrings on orbifolds with four non-compact dimensions and $N=1$ supersymmetry. In this paper, we concentrate on a non-trivial Z_2xZ_2 example. We show that consistency conditions, arising from…

We present four-dimensional M-theory vacua with N>0 supersymmetry which, from the perspective of perturbative Type IIA string theory, have N=0. Such vacua can appear when the compactifying 7-manifold is a U(1) fibration. The missing…

We construct a new class of non-supersymmetric ten-dimensional type II flux vacua, by studying first order differential equations which are deformations of the $\mathcal{N}=1$ supersymmetry conditions. We do so within the context of…

A while ago, examples of N=1 vacua in D=6 were constructed as orientifolds of Type IIB string theory compactified on the K3 surface. Among the interesting features of those models was the presence of D5-branes behaving like small…

We review the construction and phenomenology of intersecting brane worlds. The breaking of chiral and supersymmetry together with a reduction of gauge symmetry by introducing D-branes at generic angles into type I or type II string…