Related papers: Three-Generation Super No-Scale Models in Heteroti…
We discuss the construction of heterotic--string models that allow for the existence of an extra $Z^\prime$ at low scales. One of the main difficulties encountered is that the desired symmetries tend to be anomalous in the prevailing three…
We construct a general class of chiral four-dimensional string models with Scherk--Schwarz supersymmetry breaking, involving freely acting orbifolds. The basic ingredient is to combine an ordinary supersymmetry-preserving Z_N projection…
The free fermionic construction of the heterotic string in four dimensions produced a large space of three generation models with the underlying $SO(10)$ embedding of the Standard Model states. The $SO(10)$ symmetry is broken to a subgroup…
We construct non-supersymmetric type I string models which correspond to consistent flat-space solutions of all classical equations of motion. Moreover, the one-loop vacuum energy is naturally fixed by the size of compact extra dimensions…
We study the cosmological constant problem in a three-dimensional N=2 supergravity theory with gauge group SU[2]_{global}xU[1]_{local}. The model we consider is known to admit string-like configurations, the so-called semi-local cosmic…
We propose a supersymmetric technicolor model in which the electroweak symmetry breaking is communicated to the quarks and leptons by technicolored $SU(2)_W$-singlet scalars. When the technifermions condense, the quarks and leptons of the…
We search for the three-generation standard-like and/or Pati-Salam models from the $SO(32)$ heterotic string theory on smooth, quotient complete intersection Calabi-Yau threefolds with multiple line bundles, each with structure group…
We perform a complete global phenomenological analysis of a realistic string-inspired model based on the supersymmetric Pati-Salam $SU(4)\times SU(2)_L \times SU(2)_R$ gauge group supplemented by a U(1) family symmetry, and present…
Recently, we presented the first non-Abelian flat directions that produce from a heterotic string model solely the three-generation MSSM states as the massless spectrum in the observable sector of the low energy effective field theory. In…
We search for supersymmetric standard model realizations with extra singlets and extra $ U(1)$ using the heterotic string compactification on the $ Z_{6-II}$ orbifold with two Wilson lines. We analyze the vacuum restabilization mechanism…
We analyse the experimental limits on the breaking scale of Pati-Salam extensions of the Standard Model. These arise from the experimental limits on rare-meson decay processes mediated at tree-level by the vector leptoquark in the model.…
We investigate under which conditions the cosmological constant vanishes perturbatively at the one-loop level for heterotic strings on non-supersymmetric toroidal orbifolds. To obtain model-independent results, which do not rely on the…
The main aspects of a recently developed method for classification of heterotic superstring vacua in the Free Fermionic Formulation are presented. Using these techniques we classify a big number of approximately $10^{15}$ heterotic string…
We discuss a minimal renormalizable Pati-Salam theory based on the $SU(4)_{\rm C}\,\times\,SU(2)_{\rm L}\,\times\,SU(2)_{\rm R}$ gauge group, with unification scale Higgs multiplets taken as $SU(2)_{\rm L}$ and $SU(2)_{\rm R}$ doublets,…
Using the superfield formalism and implementing the canonical noncommutativity, the Kahlerian effective superpotential is evaluated in the three-dimensional noncommutative supersymmetric Chern--Simons-matter model at the two-loop order. The…
The assumption that space-time is a noncommutative space formed as a product of a continuous four dimensional manifold times a finite space predicts, almost uniquely, the Standard Model with all its fermions, gauge fields, Higgs field and…
We explore supersymmetric Type I string-motivated three-family scenarios in which the Standard Model is embedded within two sets of intersecting D branes with U(1)-extended Pati-Salam gauge groups. We study a model inspired by the Shiu-Tye…
We study the minimal set of Higgs scalars, for models based on the local gauge group $SU(3)_c \otimes SU(3)_L \otimes U(1)_X$ which do not contain particles with exotic electric charges. We show that only two Higgs $SU(3)_L$ triplets are…
We examine the problem of supersymmetry breaking in realistic superstring standard--like models which are constructed in the free fermionic formulation. We impose a supersymmetric vacuum at the Planck scale by requiring vanishing F and D…
Over the past three decades, considerable effort has been devoted to studying the rich and diverse phenomenologies of heterotic strings exhibiting spacetime supersymmetry. Unfortunately, during this same period, there has been relatively…