Related papers: Coupling Constant Unification and LEP Data
We analyze the implications of the light gluino scenario for the unification of gauge and Yukawa couplings within the minimal supersymmetric standard model. Within this scheme all fermionic supersymmetric particles are naturally light,…
The natural grand unified theories solve various problems of the supersymmetric grand unified theory and give realistic quark and lepton mass matrices under the natural assumption that all terms allowed by the symmetry are introduced with…
We extend to larger unification groups an earlier study exploring the possibility of unification of gauge symmetries in theories with dynamical symmetry breaking. Based on our results, we comment on the outlook for models that seek to…
The evolution of Standard Model gauge couplings is studied in a non-supersymmetric scenario in which the hierarchy problem is resolved by Higgs compositeness above the weak scale. It is argued that massiveness of the top quark combined with…
We consider $b$-$\tau$ unification in supersymmetric $SU(5)$ grand unified theories (GUTs) with extra matters. The renormalization group runnings of $b$ and $\tau$ Yukawa coupling constants may be significantly affected by the existence of…
If there is an extra U(1) gauge symmetry broken at low energies, then it may be possible from the charges of the known quarks and leptons under this U(1) to make inferences about how much gauge unification occurs at high scales and about…
We discuss the possibility of unifying in a simple and economical manner the Yukawa couplings of third generation fermions in a non-supersymmetric SO(10) model with an intermediate symmetry breaking, focusing on two possible patterns with…
We propose a simple renormalizable grand unified theory based on the $SU(5)$ gauge symmetry where the neutrino masses are generated at the quantum level through the Zee mechanism. In this model the same Higgs needed to correct the mass…
We propose an alternative unification scenario where the Higgs self-coupling (lambda) is unified with the electroweak SU(2)L x U(1)Y interactions at an intermediate scale MGH, lower than the GUT scale. In this model the SM remains valid up…
The lower limit to string coupling unification in weakly coupled heterotic strings was shown by Kaplunovsky to be around Lambda_H ~ 5 x 10^{17} GeV. In contrast, under the scenario of an intermediate scale desert, the SU(3)_C x SU(2)_L x…
We present a model based on the gauge group SU(2)_L\times SU(2)_R \times SU(4)_C with gauge couplings that are found to be unified at a scale near the string unification scale. This model breaks to the MSSM at an intermediate scale which is…
Using an analogy between Bogomol'nyi bound and the harmonic oscillator in quantum mechanics we propose a possible explanation of the coupling constant numerical value at the grand unification scale. It is found to be $1/8\pi$.
Various ideas support the notion that the GUT gauge group might be a semi-simple direct-product group such as $SU(5) \times SU(5)$. The doublet-triplet splitting problem can be solved with a direct product group. String theory suggests that…
We analize the impact of two-loop renormalization group equations on the $SU(3)_c\times SU(2)_w\times U(1)_Y$ gauge couplings unification in various supersymmetric theories. In general the presence of superfields in higher representation…
Gauge coupling unification misleads infrared observers if new gauge bosons do not simultaneously come into the spectrum. Though easy to engineer in gauge theory, the situation in string theory is nuanced, due to moduli dependence. We study…
The simplest Gauge-Higgs Unification model is a five-dimensional SU(2) gauge theory compactified on the S^1/Z_2 orbifold, such that on the four-dimensional boundaries of space-time there is an unbroken U(1) symmetry and a complex scalar,…
Supersymmetric extensions of the Standard Model generally give a theoretical upper limit on the lightest Higgs boson mass which may be uncomfortably close to the current experimental lower bound of $m_h$ > 114 GeV. Here we show ways in…
A new supersymmetric gauge model is proposed with particle content chosen only from the 27 and 27* representations of E_6. The gauge symmetry SU(3) X SU(2)_L X SU(2)_R X U(1) is realized at the TeV energy scale and the gauge couplings…
We present an updated assessment of the viability of t-b-tau Yukawa coupling unification in supersymmetric models. For the superpotential Higgs mass parameter mu>0, we find unification to less than 1% is possible, but only for GUT scale…
We discuss the impact of the recent precision measurements at LEP on the minimal supersymmetric standard model. We show that the values of $\tan\beta$ necessary to induce large positive corrections to $R_b$ are the same as the ones…