Related papers: A Solution to the Polonyi Problem in the Minimum S…
We show that one of the ways of obtaining consistency between the idea of supersymmetric grand unification and an apparent low value of $\alpha_{strong}(M_Z)\simeq .11$ indicated by several low energy experiments is to have an intermediate…
A natural model of realizing the effective supersymmetry is presented. Two sets of the Standard Model-like gauge group $G_1\times G_2$ are introduced, where $G_i=SU(3)_i\times SU(2)_i\times U(1)_i$, which break diagonally to the Standard…
For the minimal $\lambda$-supersymmetry, it stays perturbative to the GUT scale for $\lambda \leq 0.7$. This upper bound is relaxed when one either takes the criteria that all couplings close to $\sim 4\pi$ for non-perturbation or allows…
A simple extension of the minimal renormalizable supersymmetric SO(10) grand unified theory by adding a 120-dimensional Higgs representation is examined. This brings new antisymmetric contributions to the relevant quark and lepton mass sum…
LHC constraints on the recently proposed SUSY SO(10) GUT model with top-bottom-tau Yukawa unification are investigated. In this model, various phenomenological constraints are in concord with the Yukawa unification thanks to the negative…
In the $SO(5) \times U(1)$ gauge-Higgs unification in the Randall-Sundrum (RS) warped space the Higgs boson naturally becomes stable. The model is consistent with the current collider signatures only for a large warp factor $z_L > 10^{15}$…
Nowadays in the MSSM the moderate values of $\tan\beta$ are almost excluded by LEP II lower bound on the lightest Higgs boson mass. In the Next-to-Minimal Supersymmetric Standard Model the theoretical upper bound on it increases and reaches…
Gauge mediation of supersymmetry breakdown has many attractive features and can be realized in phenomenologically interesting string-motivated models. We point out that in models with the Polonyi-like field stabilized at a low expectation…
We study the NMSSM with universal Susy breaking terms (besides the Higgs sector) at the GUT scale. Within this constrained parameter space, it is not difficult to find a Higgs boson with a mass of about 125 GeV and an enhanced cross section…
I discuss a renormalisable model based on $\Delta(27)$ family symmetry with an $SO(10)$ grand unified theory (GUT) with spontaneous geometrical $CP$ violation. The symmetries are broken close to the GUT breaking scale, yielding the minimal…
In the MSSM, the assumptions of a common sfermion mass parameter m_0 and a common gaugino mass parameter m_1/2, along with the requirements from radiative electroweak symmetry breaking, lead to relatively large values of the Higgs mixing…
The Higgs naturalness problem is solved if the growth of Einstein's gravitational interaction is softened at an energy $ \lesssim 10^{11}\,$GeV (softened gravity). We work here within an explicit realization where the Einstein-Hilbert…
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…
We use the Higgs coupling and the muon anomalous magnetic moment measurements to constrain the parameter space of the natural supersymmetry (SUSY) in the Generalized Minimal Supergravity (GmSUGRA) model. We scan the parameter space of the…
Without supersymmetry, the gauge couplings in the standard model with five Higgs doublets unify around 10^14 GeV. In this case, the trinified model, SU(3)_C x SU(3)_L x SU(3)_R x Z_3, with the minimal Higgs sector required for symmetry…
In minimal SUSY-GUT models with $M_{SUSY}\alt 1$ TeV, the renormalization group equations have a solution dominated by the infrared fixed point of the top Yukawa coupling. This fixed point predicts $m_t\simeq (200\; {\rm GeV})\sin \beta $;…
We perform global fits to the most recent data (after summer 2014) on Higgs boson signal strengths in the framework of the minimal supersymmetric standard model (MSSM). We further impose the existing limits on the masses of charginos,…
We discuss an extension of the minimal Higgs triplet model with a classically conformal invariance and with a gauged $U(1)_{B-L}$ symmetry. In our scenario, tiny masses of neutrinos are generated by a hybrid contribution from the type-I and…
We show that it is possible to achieve one step gauge coupling unification in a general class of non supersymmetric models which at low energies have only the standard particle content and extra Higgs fields doublets. The constraints are…
A $Z_2$ symmetry that extends the weak interaction, $SU(2)_L \rightarrow SU(2)_L \times SU(2)'$, and the Higgs sector, $H(2) \rightarrow H(2,1) + H'(1,2)$, yields a Standard Model quartic coupling that vanishes at scale $v' = <H'>~\gg~<H>$.…