Related papers: On Mediating Supersymmetry Breaking in D-brane Mod…
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 how chiral type I models whose tadpole conditions have no supersymmetric solution can be consistently defined introducing antibranes with non-supersymmetric world volumes. At tree level, the resulting stable non-BPS configurations…
Orientable open string theories containing both bosons and fermions without the GSO projection are expected to have the 10 dimensional N=2(A) space-time supersymmetry in a spontaneously broken phase. We study the low-energy theorem for the…
In these lectures we start with a pedagogical introduction of the properties of open and closed superstrings and then, using the open/closed string duality, we construct the boundary state that provides the description of the maximally…
We construct four dimensional three generation non-supersymmetric $SU(3)_c \times SU(2)_L \times U(1)_Y$ intersecting D6-brane models with $\nu_R$\rq{s}. At three stacks we find exactly the MSSM chiral fermion matter spectrum. At 4-,…
In type IIB string theory, we consider fractional D3-branes in the orbifold background dual to four-dimensional N=2 supersymmetric Yang-Mills theory. We find the gravitational dual description of the generation of a non-trivial field theory…
We investigate left-right symmetric extensions of the standard model based on open strings ending on D-branes, with gauge bosons due to strings attached to stacks of D-branes and chiral matter due to strings stretching between intersecting…
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 consider the $(p+2)$-dimensional gauged supergravities arising as a consistent truncation of type II on $S^{8-p}$, which are associated with the near-horizon limit of D$p$-branes, for $p=2,4,5,6$ (and NS5-branes for $p=5$). In a…
We show that previous proposals to accommodate the MSSM with string theory N=0 non-supersymmetric compactifications coming from intersecting D6-branes may be made fully consistent with the cancellation of RR tadpoles. In this respect we…
D-branes intersecting at an arbitrary fixed angle generically constitute a configuration unstable toward recombination. The reconnection of the branes nucleates at the intersection point and involves a generalization of the process of brane…
In this review we describe our current understanding of the properties of open string tachyons on an unstable D-brane or brane-antibrane system in string theory. The various string theoretic methods used for this study include techniques of…
We identify the 4D field theories living on the world volume of D4 branes in non-supersymmetric type IIA string theory constructions. They are softly broken N=2 SQCD with the breakings introduced through vevs of the auxilliary fields in the…
We consider theories with one or more compact dimensions with size r > 1/M, where M is the fundamental Planck scale, with the visible and hidden sectors localized on spatially separated "3-branes." We show that a bulk U(1) gauge field…
We apply the well-known Scherk-Schwarz supersymmetry breaking mechanism in an open string context. We construct a new Z_3\times Z_3^\prime model, containing only D9-branes, and rederive from a more geometric perspective the known…
A factorization of spacetime of the form M^3xM^3xM^3 is considered in this paper as the closed string background in type IIA. The idea behind this construction is that each M^3 might give rise to one large spatial dimension of 4-dimensional…
Recent developments in string inspired models of inflation suggest that D-strings are formed at the end of inflation. Within the supergravity model of D-strings there are 2(n-1) chiral fermion zero modes for a D-string of winding n. Using…
The first part of this review tries to provide a self-contained view of supersymmetry breaking from the bottom-up perspective. We thus describe N=1 supersymmetry in four dimensions, the Standard Model and the MSSM, with emphasis on the…
We construct a class of supersymmetric boundary interactions in N=2 field theories on the half-space, which depend on parameters that are not at all renormalized or not renormalized in perturbation theory beyond one-loop. This can be used…
In this paper we incorporate gauge fields into the tachyon field theory models for unstable D-branes in bosonic and in Type II string theories. The chosen couplings yield massless gauge fields and an infinite set of equally spaced massive…