Related papers: Trinification from $\mathrm{E}_{6}$ symmetry break…
We consider the methods by which higher-level and non-simply laced gauge symmetries can be realized in free-field heterotic string theory. We show that all such realizations have a common underlying feature, namely a dimensional truncation…
In this talk, we introduce a new scenario of grand unified theory (GUT) with anomalous $U(1)_A$ gauge symmetry, which can explain doublet-triplet splitting, quark and lepton masses and mixing angles. In neutrino sector, the scenario…
Local supersymmetry (SUSY) provides an attractive framework for the incorporation of gravity and unification of gauge interactions within Grand Unified Theories (GUTs). Its breakdown can lead to a variety of models with softly broken SUSY…
We construct supersymmetric (SUSY) grand unification (GUT) models in the six dimensional space-time where the GUT symmetry is broken down to the standard-model gauge group by a simple orbifolding T^2/Z_4 or T^2/Z_6 and a pair of massless…
We consider a composite Higgs model embedded into a Grand Unified Theory(GUT) based on the E_6 gauge group. The phenomenological viability of this E_6 inspired composite Higgs model (E6CHM) implies that standard model (SM) elementary…
After a brief review of the motivations for grand unification, I discuss the main challenges facing realistic SUSY GUT model building. Achieving doublet-triplet splitting without fine--tuning is chief among them. Symmetry breaking should…
In this paper we discuss $SU(5)^{3}$ with cyclic symmetry as a possible grand unified theory (GUT). The basic idea of such a tri-unification is that there is a separate $SU(5)$ for each fermion family, with the light Higgs doublet(s)…
We consider the minimal version of an extension of the standard electroweak model based on the $SU(3)_c \times SU(3)_L \times U(1)_X$ gauge symmetry (the 3-3-1 model). We analyze the most general potential constructed from three scalars in…
Working with explicit examples given by the 56 representation in $SU(8)$, and the 10 representation in $SU(5)$, we show that symmetry breaking of a group ${\cal G}\supset {\cal G}_1 \times {\cal G}_2$ by a scalar in a rank three or two…
E6 grand unification combines the Standard Model matter and Higgs states in the single 27 representation. I discuss how the E6 structure underlies the quasi-realistic free fermion heterotic-string models. E6 -> SO(10) X U(1) breaking is…
We propose here - for the first time in the literature, to our best knowledge - an electroweak unification based on the $SU(5)_{L}\times U(1)_{Y}$ gauge group. The spontaneous symmetry breaking takes place in the manner $SU(5)_{L}\times…
Of the five exceptional groups, $\mathrm{E}_6$ is considered the most attractive for unification due to the following reasons: (i) it contains both $\mathrm{Spin} (10) \times \mathrm{U}(1)$ and $\mathrm{SU} (3) \times \mathrm{SU}(3) \times…
We argue that non-supersymmetric SO(10) models based on a renormalizable Higgs sector in which spontaneous symmetry breaking is triggered by the VEVs of a 45-dimensional adjoint and a 126-dimensional tensor representations can provide a…
In this paper we summarize the minimal supersymmetric standard model as well as the renormalization group equations of its parameters. We proceed to examine the feasability of the model when the breaking of supersymmetry is parametrized by…
The missing VEV solution to the doublet-triplet splitting problem in general SU(N) SUSY GUTs is found. Remarkably enough, it requires a strict equality of numbers of the fundamental colours and flavours in SU(N) and for the even-order…
The local Lie algebra of the Standard Model (SM) is $su(3)\times su(2) \times u(1)$, yet its global gauge group, $G_{{\rm SM}_{\rm q}}=$SU(3)$\times$SU(2)$\times$U(1)/$\mathbb{Z}_{\rm q}$, q$=1,2,3,6$ remains undetermined. Building on…
We examine the spectrum of superparticles obtained from the minimal SO(10) grand unified model, where it is assumed the gauge symmetry breaking yields the Minimal Supersymmetric Standard Model (MSSM) as the effective theory at $M_{GUT}\sim…
For supersymmetric extensions of the Standard Model we construct some expressions that include Yukawa couplings for the third and second generations and receive relatively small quantum corrections. This implies that they slightly depend on…
We show that in the framework of grand unified theory (GUT) with anomalous $U(1)_A$ gauge symmetry, the success of the gauge coupling unification in the minimal SU(5) GUT is naturally explained, even if the mass spectrum of superheavy…
We consider the possibility that the soft supersymmetry-breaking parameters m_{1/2} and m_0 of the MSSM are universal at some scale M_{in} below the supersymmetric grand unification scale M_{GUT}, as might occur in scenarios where either…