Related papers: Effect of Extra Dimensions on Gauge Coupling Unifi…
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…
The gauge coupling unification can be achieved at a unification scale around 5 x 10^{13} GeV if the Standard Model scalar sector is extended with extra Higgs-like doublets. The relevant new scalar degrees of freedom in the form of chiral Z*…
A constraint on masses of superheavy gauge and Higgs multiplets at the grand unification (GUT) scale is obtained from the gauge coupling unification in the case of high-scale supersymmetry. We found that all of the particles may lie around…
We show that the bound from the electroweak data on the size of extra dimensions accessible to all the standard model fields is rather loose. These "universal" extra dimensions could have a compactification scale as low as 300 GeV for one…
We investigate the effects of Yukawa couplings on the phenomenological predictions for a class of supersymmetric models which allows for the presence of complete SU(5) multiplets in addition to the Minimal Supersymmetric Standard Model…
We study six-dimensional (6D) SU(6) supersymmetric models where the doublet-triplet splitting, quark-lepton mass relations and gaugino-mediated supersymmetry breaking are taken into account. We find that effective 4D gauge coupling…
In contrast to the old heterotic string case, the (weakly coupled) type I brane framework allows to have all, part or none of the standard model gauge group factors propagating in large extra--dimensions of TeV$^{-1}$ size. We investigate…
The recent LEP data for gauge coupling constants constrain many grand unified models. In this paper, we study several possibilities for unification of gauge coupling constants. Without an intermediate mass scale, the minimal supersymmetric…
A brief review of the recent developments in the physics from extra dimensions is given with a focus on the effects of Kaluza-Klein excitations in the Standard Model sector. It is shown that the current accurate data on the Fermi constant…
We consider field sets that do not form complete SU(5) multiplets, but exactly preserve the one-loop MSSM prediction for $\alpha_3(M_Z)$ independently of the value of their mass. Such fields can raise the unification scale in different…
Discovery of a Higgs boson and precise measurements of its properties open a new window to test physics beyond the standard model. Models with Universal Extra Dimensions are not exception. Kaluza-Klein excitations of the standard model…
We study a gauge coupling unification scenario based on a non-supersymmetric 5-dimensional model. Through an orbifold compactification, we obtain the Standard Model with split multiplets on a 4-dimensional wall, which is compatible with a…
Interaction of bulk gravitons to Standard Model particles is examined in the scenario of warped extra dimension. It is found that the length of the extra dimension is of physical importance as it determines the decay widths of graviton…
We study 5 dimensional grand-unified theories in an orbifold geometry by the method of effective field theory: we match the low and high energy theories by integrating out at 1-loop the massive Kaluza-Klein states. In the supersymmetric…
The interpretation of the apparent unification of gauge couplings within supersymmetric theories depends on uncertainties induced through heavy particle thresholds. While in standard grand unified theories these effects can be estimated…
We motivate and explore the possibility that extra SU(N) gauge groups may exist independently of the Standard Model groups, yet not be subgroups of some grand unified group. We study the running of the coupling constants as a potential…
We study grand unified models in the five-dimensional space-time where the extra dimension is compactified on $S^1/Z_2$. The spontaneous breaking of unified gauge symmetries is achieved via vacuum expectation values of the extra-dimensional…
We examine gauge and Yukawa coupling unification in models with gauge-mediated supersymmetry breaking. We work consistently to two-loop order, and include all weak, messenger and unification-scale threshold corrections. We find that…
We show that contrary to first expectations realistic three generation supersymmetric intersecting brane world models give rise to phenomenologically interesting predictions about gauge coupling unification. Assuming the most economical way…
We study the low energy evolution of coupling constants of the standard model and show that gauge coupling unification can be achieved at the electroweak scale with a suitable normalization. We choose the grand unification group to be the…