grand unification theory

(redirected from GUT scale)
Related to GUT scale: Planck mass

grand′ unifica′tion the`ory


n.
a hypothetical quantum theory that would encompass the electroweak theory and the strong force.
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In these models a number of fermion or scalar masses below the GUT scale have been utilised to achieve unification.
In contrast to the popular belief on low proton lifetime prediction of the minimal SU(5) [35], we estimate new precise and enhanced predictions of this model including threshold effects [100-108] of heavy particles near the GUT scale. Predicted lifetimes are found to be within the accessible ranges of Superkamiokande and Hyperkamiokande experimental search programmes [109].
Similarly the GUT scale is now determined with high precision including all possible theoretical and experimental uncertainties.
Thus, in order to safeguard precision unification, it is essential that [mathematical expression not reproducible] in the present scalar extended SU(5) model (the upper limit is due to our observation that type-II seesaw scale is lower than the GUT scale although, strictly speaking, [mathematical expression not reproducible] is possible if type-II seesaw contribution to neutrino mass is ignored).
We dedicate an additional subsection to the calculation of typical fine tuning and expectations for the scale of the superpartners in models constrained at the GUT scale. We summarize the main treated points and conclude in Section 4.
Besides, with gaugino universality at the GUT scale, it is a struggle to fully accommodate the measured value of the Higgs mass at the LHC [47, 51] (this problem is resolved if the gluino mass is a free parameter, e.g., [52]).
We have chosen to show in Figure 4 the higgsino parameter space under CMSSM boundary conditions, which provide a reasonable ansatz for models with scalar universality inspired by supergravity, and more generally cast in a lean framework scenarios in which supersymmetry breaking is transmitted to the visible sector at some high scale (the GUT scale) and EWSB is obtained radiatively around the minima of the MSSM scalar potential.
Very heavy winos/binos at the GUT scale feed through the RGE on the low-scale value of the soft SUSY-breaking up-type Higgs doublet mass, which carry SU(2) isospin and hypercharge and also tend to push down the right-handed stop mass.
Thus the GUT scale symmetry breaking SO(10) [right arrow] [G.sub.224D] can occur by the VEV of [54.sub.H] in the direction (%) ~ MGUT, but SO(10) [right arrow] [G.sub.224] can occur by the VEV of [210.sub.H] in the direction <[[eta].sub.o]> ~ [M.sub.GUT].
In this symmetry breaking pattern all LH triplets and doublets is near the GUT scale, but RH triplets or doublets are near the [G.sub.2213] breaking intermediate scale [M.sub.R] which could be ~(few-100) TeV.
A special feature of this linear seesaw, compared to others [39, 40, 44], is that the neutrino mass formula is suppressed by the SUSY GUT scale but it is decoupled from the low U[(1).sub.B-L] breaking scale.
A special feature of this linear seesaw, compared to others [39,40], is that the neutrino mass formula is suppressed by the SUSY GUT scale but decoupled from the low U[(1).sub.B-L] breaking scale which can be even at ~few TeV.