Related papers: Standard Model Engineering with Intersecting Brane…
The supersymmetric extension of the standard model suffers from a problem of baryon-number violation. Discrete (and global) symmetries introduced to protect the proton are unstable under gravitational effects. We add a gauged $U(1)_X$ to…
A remarkable U(1) gauge extension of the supersymmetric standard model was proposed eight years ago. It is anomaly-free, has no mu term, and conserves baryon and lepton numbers automatically. The phenomenology of a specific version of this…
We combine two popular extensions of beyond the Standard Model physics within the framework of intersecting D6-brane models: discrete Zn symmetries and Peccei-Quinn axions. The underlying natural connection between both extensions is formed…
We elaborate on a recent study of a model of supersymmetry breaking we proposed recently, in the presence of a tunable positive cosmological constant, based on a gauged shift symmetry of a string modulus, external to the Standard Model (SM)…
We investigate a simple theory where Baryon number (B) and Lepton number (L) are local gauge symmetries. In this theory B and L are on the same footing and the anomalies are cancelled by adding a single new fermionic generation. There is an…
We perform a systematic search for globally defined MSSM-like and left-right symmetric models on D6-branes on the T6/Z(2)xZ(6)xOR orientifold with discrete torsion. Our search is exhaustive for models that are independent of the value of…
U(1)-family symmetries have led to successful predictions of the fermion mass spectrum and the mixing angles of the hadronic sector. In the context of the supersymmetric unified theories, they further imply a non-trivial mass structure for…
Recently it was pointed out that in the TeV-scale brane world there is a logical possibility where the electroweak Higgs can be identified with a fourth generation slepton. In this paper we address various issues in this four-generation…
We propose a renormalizable theory with minimal particle content and symmetries, that successfully explains the number of Standard Model (SM) fermion families, the SM fermion mass hierarchy, the tiny values for the light active neutrino…
A systematic approach is followed in order to identify realistic D-brane models at toric del Pezzo singularities. Requiring quark and lepton spectrum and Yukawas from D3 branes and massless hypercharge, we are led to Pati-Salam extensions…
After reviewing the general structure of supersymmetric intersecting brane world models, we discuss the issue of stringy gauge coupling unification for a natural class of MSSM-like models.
A new non-universal abelian extension $\mathrm{G_{SM}}\otimes \mathrm{U(1)}_{X}$ to the Standard Model free from chiral anomalies is presented. The new $X$ charges distinguish among generations so as the fermion mass matrices get…
We review efforts in string model building, focusing on the heterotic orbifold compactifications. We survey how one can, starting from an explicit string theory, obtain models which resemble Nature. These models exhibit the standard model…
Based on the low-energy effective field theory of D-branes, the mass spectrum of an extended Standard Model with two-Higgs doublets used to generate all the mass terms is investigated. Besides the gauge bosons, the fermion mass spectrum is…
We explore the anomaly-cancellation constraints on simplified dark matter (DM) models with an extra U(1)$^\prime$ gauge boson $Z'$. We show that, if the Standard Model (SM) fermions are supplemented by a single DM fermion $\chi$ that is a…
I discuss the construction of realistic superstring standard--like models in the four dimensional free fermionic formulation. I discuss the massless spectrum of the superstring standard--like models and the texture of fermion mass matrices.…
A fermion-boson-type composite model for quarks and leptons is proposed. Elementary fields are only one kind of spin-1/2 and spin-0 preon. Both are in the global supersymmetric pair with the common electric charge of e/6 and belong to the…
A new nontrivial U(1) gauge extension of the Minimal Supersymmetric Standard Model (MSSM) is proposed which automatically conserves baryon number and lepton number, and solves the mu problem. Naturally small Dirac neutrino masses are also…
A common way to obtain standard-model-like Lagrangians in string theory is to place D3-branes inside flux compactifications. The bosonic and fermionic masses and couplings of the resulting gauge theory are determined by the ten-dimensional…
Intersecting branes have been the subject of string model building for several years. This work introduces in detail the toroidal and Z_N-orientifolds, where the main discussion employs the picture of intersecting D6-branes. The derivation…