Related papers: Road map through the desert: unification with vect…
As is well-known, Trinification, \ie, the extension of the Standard Model (SM) to $[SU(3)]^3=SU(3)_c\times SU(3)_L\times SU(3)_R$ as occurs in $E_6$ models, allows for a partial unification of the gauge forces even though quarks and leptons…
We summarize recent studies of realistic nonsupersymmetric Grand Unified Theories (GUTs) extended with a global $U(1)_{\rm PQ}$ symmetry, so as to accommodate the axion solution to the strong CP problem. Aside from solving the CP problem…
We consider the $SU(6)$ GUT model as an explanation for the diphoton final state excess, where the masses of all associated particles are linked with a new symmetry breaking scale. In this model, the diphoton final states arise due to loops…
$U(1)^\prime$ extensions of the standard model with generation-dependent couplings to quarks and leptons are investigated as an explanation of anomalies in rare $B$-decays, with an emphasis on stability and predictivity up to the Planck…
In preon models based on chiral gauge theories, we show that light composite fermions can ensue as a result of gauging a subset of preons in a vector-like manner. After demonstrating how this mechanism works in a toy example, we construct a…
We study extensions of the Standard Model with general new vector bosons. The full Standard Model gauge symmetry is used to classify the extra vectors and constrain their couplings. We derive the corresponding effective Lagrangian, valid at…
We investigate constraints that the requirements of perturbativity and gauge coupling unification impose on extensions of the Standard Model and of the MSSM. In particular, we discuss the renormalization group running in several SUSY…
We consider a neutrinophilic $U(1)$ extension of the standard model (SM) which couples only to SM isosinglet neutral fermions, charged under the new group. The neutral fermions couple to the SM matter fields through Yukawa interactions. The…
New dark sectors consisting of exotic fields that couple only very feebly to the Standard Model (SM) have strong theoretical motivation and may be relevant to explaining the abundance of dark matter (DM). An important question for such…
We investigate the possibility that unification occurs at strong coupling. We show that, despite the fact the couplings pass through a strong coupling regime, accurate predictions for their low energy values are possible because the…
An analytic computation is given of the generation of Yukawa couplings and of the quark, charged lepton and neutrino masses in the framework of an SO(10) model with a unified Higgs sector consisting of a single pair of vector-spinor $144 +…
We study perturbative unitarity constraints on general W' models by considering the high energy behavior of fermion scattering into gauge bosons. In most cases we survey, a Z' boson with a comparable mass must be present for the theory to…
The standard model extended by three vector-like families with masses of order 1 TeV -- 100 TeV allows for unification of gauge couplings. The values of gauge couplings at the electroweak scale are highly insensitive to fundamental…
We consider the unification of gauge, Higgs as well as the matter fields in a 6D N=2 supersymmetric SU(8) gauge theory. The gauge symmetry SU(8) is broken down to SU(4) x SU(2)_L x SU(2)_R x U(1)^2 in 4D through T^2/Z_6 orbifold…
Beyond Standard Model theories describing the electro-weak sector must exhibit a large separation of scales (or "walking") to account for a light, 125 GeV Higgs boson and the fact that so far no other resonances have been observed. Large…
The inconsistence of Dirac-Weyl field equations with the universal U(1) gauge invariance of neutrinos in quantum mechanics led to generalize the special relativity to the generic relativity, which was composed of the special relativity and…
It was shown recently that the original SU(5) theory of Georgi and Glashow, augmented with an adjoint fermionic multiplet 24_F, can be made compatible both with neutrino masses and gauge coupling unification. In particular, the model…
We develop a bottom-up approach to constructing a theory of fermion masses and mixing angles based on the gauge group $SU(3)\times G$ where SU(3) is a family symmetry and $G$ contains a unified group such as SO(10) or its Pati-Salam…
We investigate the status of predictive fermion mass ansatzes which make use of the grand unification scale conditions $m_e=m_d/3$, $m_\mu =3m_s$, and $\mid V_{cb}\mid =\sqrt{m_{c}/m_{t}}$ in non-supersymmetric SO(10) grand unification. The…
We show that in SO(10) models, a Yukawa sector consisting of a real $10_H$, a real $120_H$ and a complex $126_H$ of Higgs fields can provide a realistic fit to all fermion masses and mixings, including the neutrino sector. Although the…