Related papers: Standard-like Models with Broken Supersymmetry fro…
We propose a new mechanism of spontaneous supersymmetry breaking. The existence of extra dimensions with nontrivial topology plays an important role. We investigate new features resulted from the mechanism in two simple supersymmetric Z_2…
In this thesis, we study aspects of D-brane realizations of the Standard Model. Specifically, we study orientifold models with rotation and translation elements that break supersymmetry, provide the general consistency conditions and derive…
We propose a new class of models with gauge mediated supersymmetry breaking, the cascade supersymmetry breaking. This class of models is consistent with the gravitino mass as low as O(1)eV without having suppressed gaugino masses, nor the…
We investigate the D-brane contents of asymmetric orbifolds. Using T-duality we find that the consistent description of open strings in asymmetric orbifolds requires to turn on background gauge fields on the D-branes. We derive the…
In Type II string vacua constructed from intersecting/magnetized D-branes, the supersymmetry-breaking soft terms are genericaly non-universal. It is shown that universal supersymmetry-breaking soft terms may arise in a realistic MSSM…
In the presence of internal magnetic fields, a D9 brane can acquire a D5 (or anti-D5) R-R charge, and can therefore contribute to the corresponding tadpole. In the resulting vacua, supersymmetry is generically broken and tachyonic…
We show that for supersymmetric AdS vacua on Type IIA orientifolds with flux compactifications, the RR tadpole cancellation conditions can be completely relaxed, and then the four-dimensional N=1 supersymmetry conditions are the main…
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…
I discuss two types of non-supersymmetric string model constructions that give at low energy exactly the Standard model (SM) with no additional matter/and or gauge group factors. The construction is based on D6 branes intersecting at angles…
We construct a one-parameter set of intersecting D4-brane models, with six stacks, that yield the (non-supersymmetric) standard model plus extra vector-like matter. Twisted tadpoles and gauge anomalies are cancelled, and the model contains…
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 configurations of NS-, D4-, and D6-branes in type IIA string theory, realizing the recently discussed non-supersymmetric meta-stable minimum of 4d N=1 SU(N_c) super-Yang-Mills theories with massive flavors. We discuss their…
We analyze the conditions to have no-scale supersymmetry breaking solutions of type IIA and IIB supergravity compactified on manifolds of SU(3)-structure. The supersymmetry is spontaneously broken by the intrinsic torsion of the internal…
We consider quiver gauge theories arising on D-branes at simple Calabi-Yau singularities (quotients of the conifold). These theories have metastable supersymmetry breaking vacua. The field theoretic mechanism is basically the one exhibited…
This thesis studies meta- and exactly stable supersymmetry breaking mechanisms in heterotic and type IIB string theories and constructs an F-theory Grand Unified Theory model for neutrino physics in which neutrino mass is determined by the…
We propose a mechanism for mediating supersymmetry breaking in Type I string constructions. The basic set-up consists of a system of three D-branes: two parallel D-branes, a matter D-brane and a source D-brane, with supersymmetry breaking…
We construct eight-stack intersecting D5-brane models, with an orbifold transverse space, that yield the (non-supersymmetric) standard model up to vector-like leptons. The matter includes right-chiral neutrinos and the models have the…
Type I string theory provides eight classes of unstable D-brane systems. We determine the gauge group and tachyon spectrum for each one, and thereby describe the gauge symmetry breaking pattern in the low-energy world-volume field theory.…
We present a simple scheme for constructing models that achieve successful gauge mediation of supersymmetry breaking. In addition to our previous work [1] that proposed drastically simplified models using metastable vacua of supersymmetry…
In this thesis we investigate some aspects of the dramatic consequences of supersymmetry breaking on string vacua. In particular, we focus on the issue of vacuum stability in ten-dimensional string models with broken, or without,…