Related papers: Probing mu-term Generation Mechanism in String Mod…
In string compactification preserving N=1 SUSY, moduli fields are plausible candidates for the messenger of SUSY breaking at low energy scales. In a scenario that moduli-mediated SUSY breaking is significant, the pattern of soft SUSY…
This paper provides an overview to three recent papers on the bottom up approach to GUTs in F-theory. We assume only a minimal familiarity with string theory and phenomenology. After explaining the potential for predictive string…
A new formalism for construction of the stationary solutions is developed for the four-dimensional gravity coupled to the dilaton, Kalb-Ramond and two Maxwell fields in a low-energy heterotic string theory form. The result of generation is…
Applied to the electroweak interactions, the theory of Lie algebra extensions suggests a mechanism by which the boson masses are generated without resource to spontaneous symmetry breaking. It starts from a gauge theory without any…
Strongly coupled heterotic $E_8\times E_8$ string theory, compactified to four dimensions on a large Calabi-Yau manifold ${\bf X}$, may represent a viable candidate for the description of low-energy particle phenomenology. In this regime,…
We consider the factorization method in the spontaneously broken gauge theories such as the electroweak theory. Using the of\/f-shell $W$-boson density matrix formalism we demonstrate that the factorization conditions are completely under…
The motivation for Calabi-Yau-like compactifications of the weakly coupled $E_8\otimes E_8$ heterotic string theory, its particle spectrum and the issue of dilaton stabilization are briefly reviewed. Modular invariant models for hidden…
In supersymmetric models a tree-level neutrino mass could originate from the (weak-scale) superpotential. We propose and examine a realization of that idea, which arises naturally in the framework of a spontaneously broken U(1) R-symmetry.…
Electroweak baryogenesis has become a topic of much recent activity [1]. Here we discuss a new scenario which has the advantage of being insensitive to the order of the electroweak phase transition. We briefly review a mechanism [2] using…
We show that a cosmic string associated with spontaneous $U(1)_R$ symmetry breaking gives a constraint for supersymmetric model building. In some models, the string can be viewed as a tube-like domain wall with a winding number…
We consider an electroweak model based on the gauge symmetry SU(2)_L X U(1)_Y' X U(1)_B-L which has right-handed neutrinos with different exotic B-L quantum numbers. Because of this particular feature we are able to write Yukawa terms, and…
We propose an extension of the electroweak sector of the Standard Model in which the gauge group $SU(2)_L$ is promoted to $SU(2)_1 \times SU(2)_2$. This framework naturally includes a viable dark matter candidate and generates neutrino…
We perform a three dimensional lattice simulation of the electroweak symmetry breaking process through a two-step phase transition, where one of the two steps is a first order phase transition. Our results show that: 1) when the electroweak…
Sequestering is a promising mechanism in 4D string models to reconcile high-scale inflation with low-energy supersymmetry. In this scenario the MSSM lives on branes at singularities and it is sequestered from the sources of supersymmetry…
Many models of physics beyond the Standard Model predict minicharged particles to which current and near future low-energy experiments are highly sensitive. Such minicharges arise generically from kinetic-mixing in theories containing at…
We present explicit examples of semi-realistic heterotic models with spontaneously broken supersymmetry, which dynamically lead to breaking scales much smaller than $M_{\rm Planck}$ and exponentially small positive values for the…
The electromagnetic structure of axial-vector mesons is investigated via elastic and two-photon transition form factors (TFFs). To this end, we employ a framework based on the Dyson-Schwinger and Bethe-Salpeter equations within a contact…
The Standard Model data suggests the realization of grand unification structures in nature, in particular that of SO(10). A class of string vacua that preserve the SO(10) embedding, are the three generation free fermion heterotic-string…
We continue our study of the low energy implications of $M$ theory vacua on $G_2$ manifolds, undertaken in \cite{Acharya:2007rc,Acharya:2006ia}, where it was shown that the moduli can be stabilized and a TeV scale generated, with the Planck…
The physical motivations and the basic construction rules for Type I strings and M-theory compactifications are reviewed in light of the recent developments. The first part contains the basic theoretical ingredients needed for building…