Related papers: Split extended supersymmetry from intersecting bra…
A generic prediction of models where supersymmetry is broken at scales within a few orders of magnitude of the weak scale and is fed down to the observable sector by gauge interactions is the existence of superconducting cosmic strings…
We give a classification of all multiple intersections of D-branes in ten dimensions and M-branes in eleven dimensions that corresponds to threshold BPS bound states. The residual supersymmetry of these composite branes is determined. By…
The WW scattering into gravitino and gaugino is here investigated in the broken phase, by using both gauge and mass eigenstates. Differently from what is obtained for unbroken gauge symmetry, we find in the scattering amplitudes new…
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…
In the context of supersymmetric $SO(10)$ grand unified models, it is shown that the gauge symmetry breaking as well as a natural doublet--triplet splitting can be achieved with a minimal Higgs system consisting of a single adjoint and a…
We propose a scenario of the electroweak symmetry breaking by one-loop radiative corrections in a class of string models with D3-branes at non-supersymmetric orbifold singularities with the string scale in TeV region. As a test example, we…
We study the transition between parallel and intersecting branes on a torus. Spontaneous symmetry breaking of nonabelian gauge symmetry is understood as brane separation, and a more general intermediate deformation is discussed. We argue…
We study the possibility that supersymmetry is broken via a gaugino condensate in four dimensional string theories. We derive an effective low-energy theory describing the Goldstone mode associated with the R-symmetry breaking driven by…
We consider $SU(N)$ $\mathcal{N}=4$ super Yang-Mills with cubic and quadratic soft SUSY breaking potential, such that the global $SU(4)_R$ is broken to $SU(3)$ or further. As shown recently, this set-up supports a rich set of non-trivial…
We construct a calculable model of electroweak symmetry breaking in which the Higgs doublet emerges from the meta-stable SUSY breaking sector as a pseudo Nambu-Goldstone boson. The Higgs boson mass is further protected by the little Higgs…
In the context of the field theory limit of superstrings, we consider an almost realistic model of supersymmetry breaking by gaugino condensation which includes, through nonperturbative corrections to the K\"ahler potential, dilaton…
We study the non-linear realization of supersymmetry. We classify all lower dimensional operators, describing effective interactions of the Goldstino with Standard Model fields. Besides a universal coupling to the energy momentum tensor of…
This Ph.D. thesis investigates effective field and string theories in which supersymmetry is realized and broken in various ways. Chapter 1 addresses effective theories with nonlinearly realized supersymmetry, constructed using the…
We perform a systematic study of the Standard Model embedding in a D-brane configuration of type I string theory at the TeV scale. We end up with an attractive model and we study several phenomenological questions, such as gauge coupling…
We study the mass spectrum of superparticles within supersymmetric grand unified models. For gaugino masses, it is pointed out that the GUT-relation in the $SU(5)$ model is applicable to a more general case where a grand-unified gauge group…
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…
Natural supersymmetry with light higgsinos is most likely to emerge from the string landscape since the volume of scan parameter space shrinks to tiny volumes for electroweak unnatural models. Rather general arguments favor a landscape…
The lack of evidence for new physics beyond the standard model at the LHC points to a paucity of new particles near the weak scale. This suggests that the weak scale is tuned and that supersymmetry, if present at all, is realized at higher…
We propose a mechanism of Higgsless gauge symmetry breaking with a large mass hierarchy. We consider a 5D gauge theory on an orbifold $S^1/Z_2$. The gauge symmetry is broken by orbifolding and also nontrivial boundary conditions at fixed…
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…