Related papers: Autoencoder-Driven Clustering of Intersecting D-br…
In a geometrical background, D-brane charge is classified by topological K-theory. The corresponding classification of D-brane charge in an arbitrary, nongeometrical, compactification is still a mystery. We study D-branes on…
We construct compact type IIB orientifolds with discrete groups Z_4, Z_6, Z_6', Z_8, Z_12 and Z_12'. These models are N=1 supersymmetric in D=4 and have vector structure. The possibility of having vector structure in Z_N orientifolds with…
Employing new scanning methods, we revisit the systematic construction of three-family $N=1$ supersymmetric Pati-Salam models in Type IIA orientifolds on ${\bf T}^6/(\mathbb Z_2\times \mathbb Z_2)$ with intersecting D6-branes. Arising from…
We present special classes of orientifold models involving supersymmetry breaking via branes at angles. Type II superstring theories are compactified on a two torus times a four-dimensional orbifold. Combining worldsheet parity with a…
Most intersecting D-brane vacua in the literature contain additional massless adjoint fields in their low energy spectrum. The existence of these additional fields make it difficult to obtain negative beta functions and, eventually,…
We study recombinations of D-brane systems intersecting at more than one angle using super Yang-Mills theory. We find the condensation of an off-diagonal tachyon mode relates to the recombination, as was clarified for branes at one angle in…
We show that M-theory on spaces with irreducible holonomy represent Type IIA backgrounds in which a collection of D6-branes wrap a supersymmetric cycle in a manifold with a holonomy group different from the one appearing in the M-theory…
We study a certain class of four-dimensional N=1 supersymmetric orientifolds for which the world-sheet parity transformation is combined with a complex conjugation in the compact directions. We investigate in detail the orientifolds of the…
In this article, which is based on the first part of my PhD thesis, I review the statistics of the open string sector in T^6/(Z_2xZ_2) orientifold compactifications of the type IIA string. After an introduction to the orientifold setup, I…
Various topological properties of D-branes in the type--IIA theory are captured by the topologically twisted B-model, treating D-branes as objects in the bounded derived category of coherent sheaves on the compact part of the target space.…
We derive the rules to construct type IIB compact orientifolds in six and four dimensions including D-branes and anti-D-branes. Even though the models are non-supersymmetric due to the presence of the anti-D-branes, we show that it is easy…
We consider four-dimensional N=1 field theories realized by type IIA brane configurations of NS-branes and D4-branes, in the presence of orientifold six-planes and D6-branes. These configurations are known to present interesting effects…
Intersecting D6-brane models without discrete torsion typically suffer from unstabilized open string moduli, arising from D-brane positions and Wilson lines. These moduli generate additional massless adjoint fields, obstructing the…
In this paper we study the N=1 supersymmetric field theories realized on the world-volume of type IIB D3-branes sitting at orientifolds of non-orbifold singularities (conifold and generalizations). Several chiral models belong to this…
We study D1-branes on the fourfold $\C^4/(\Z_2\times\Z_2\times\Z_2)$, in the presence of discrete torsion. Discrete torsion is incorporated in the gauge theory of the D1-branes by considering a projective representation of the finite group…
The charges of the exceptionally twisted (D4 with triality and E6 with charge conjugation) D-branes of WZW models are determined from the microscopic/CFT point of view. The branes are labeled by twisted representations of the affine…
Starting with the non-BPS D0-brane solution of IIB/$(-1)^{F_L}I_4$ constructed recently by Eyras and Panda we construct via T-duality the non-BPS D2-brane and D1-brane solutions of IIB/$(-1)^{F_L}I_4$ and IIA/$(-1)^{F_L}I_4$ predicted by…
In this paper we consider compactifications of type I strings on Abelian orbifolds. We discuss the tadpole cancellation conditions for the general case with D9-branes only. Such compactifications have (perturbative) heterotic duals which…
The discrete tensorial charges carried by orientifold planes define n-gerbes in space-time. The simplest way to ensure a consistent string compactification is to require these gerbes to be flat. This results in expressions for the local…
We launch a systematic search for phenomenologically appealing string vacua with intersecting D-branes on the promising T6/Z(2)xZ(6)xOR orientifold with discrete torsion. The number of independent background lattices is reduced from six to…