Related papers: On Mediating Supersymmetry Breaking in D-brane Mod…
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 introduce new mechanisms for the communication of supersymmetry breaking via gauge interactions. These models do not require complicated dynamics to induce a nonvanishing F term for a singlet. The first class of models communicates…
We analyze a recently constructed class of D-brane theories with the fermion spectrum of the SM at the intersection of D6-branes wrapping a compact toroidal space. We show how the SM Higgs mechanism appears as a brane recombination effect…
We study the embedding of cosmic strings, related to the Abrikosov-Nielsen-Olesen vortex solution, into d=4, N=1 supergravity. We find that the local cosmic string solution which saturates the BPS bound of supergravity with $D$-term…
A quantum-mechanical technique is used within the framework of U(2) super-Yang-Mills theory to investigate what happens in the process after recombination of two D-p-branes at one angle. Two types of initial conditions are considered, one…
The supersymmetric extensions of the Standard Model can tolerate quite a large hierarchy between various supersymmetry breaking terms, a good example being the models of split supersymmetry. However, theoretical models generating such a…
We study anomaly mediated supersymmetry breaking in type IIB string theory and use our results to test the supergravity formula for anomaly mediated gaugino masses. We compute 1-loop gaugino masses for models of D3-branes on orbifold…
It has been conjectured that at the stationary point of the tachyon potential for the D-brane-anti-D-brane pair or for the non-BPS D-brane of superstring theories, the negative energy density cancels the brane tensions. We study this…
We show that supersymmetry breaking in a class of theories with SU(N) x SU(N-2) gauge symmetry can be studied in a calculable sigma model. We use the sigma model to show that the supersymmetry breaking vacuum in these theories leaves a…
We review the mechanisms of supersymmetry breaking mediation that occur in sequestered models, where the visible and the hidden sectors are separated by an extra dimension and communicate only via gravitational interactions. By locality,…
We construct new string vacua featuring Brane Supersymmetry Breaking, based on $T^4/\mathbb{Z}_N$ orientifolds with $\text{O}5_+$ planes and $\overline{\text{D}5}$ branes. Differently from the original construction, in these vacua the…
All the models of elementary particles and their interactions derived from String Theory involve a compact six-dimensional internal space. Its volume and shape should be fixed or stabilized, since otherwise massless scalar fields (moduli)…
We study total and partial supersymmetry breaking by freely acting orbifolds, or equivalently by Scherk-Schwarz compactifications, in type I string theory. In particular, we describe a four-dimensional chiral compactification with…
The study of discrete gauge symmetries in field theory and string theory is often carried out by embedding them into continuous symmetries. Many symmetries however do not seem to admit such embedding, for instance discrete isometries given…
We construct new supersymmetric solutions of $D$=11 supergravity describing $n$ orthogonally ``overlapping" membranes and fivebranes for $n$=2,\dots,8. Overlapping branes arise after separating intersecting branes in a direction transverse…
We discuss the construction of four dimensional non-supersymmetric models obtained from configurations of D6-branes intersecting at angles. We present the first examples of string GUT models which break exactly to the Standard Model (SM) at…
Type-IIB supergravity in ten dimensions admits two consistent $Z_2$ truncations. After the insertion of D9-branes, one of them leads to the low-energy action of type-I string theory, and it can be performed in two different ways, in…
We study D-branes of N=2 supersymmetric sigma models. Supersymmetric nonlinear sigma models with 2-dimensional target space have D0,D1,D2-branes, which are realized as A-,B-type supersymmetric boundary conditions on the worldsheet. When we…
Generic D-brane string models of particle physics predict the existence of extra U(1) gauge symmetries beyond hypercharge. These symmetries are not of the E_6 class but rather include the gauging of Baryon and Lepton numbers as well as…
"Brane supersymmetry breaking" occurs in String Theory when the only available combinations of D-branes and orientifolds are not mutually BPS and yet do not introduce tree-level tachyon instabilities. It is characterized by the emergence of…