Abstract
We discuss the Yukawa coupling unification, which can emerge in the grand unified theory, in the context of scenarios with more than one pair of Higgs doublet since the current LHC constraint has become a problem for the Yukawa unification scenarios with just one pair of Higgs doublet. More than one pair of Higgs doublets can easily arise in missing partner mechanism which solves the doublet-triplet splitting problem. In such a scenario, the Yukawa unification occurs at a medium tanβ value, e.g., ∼ 30, which corresponds to much smaller threshold corrections compared to usual large tanβ scenario for t−b−τ unification in the context of SO(10) and b−τ unification in the context of SU(5) models. Further, we show that an additional Higgs doublet pair lowers the sensitivity of the radiative symmetry breaking of the electroweak vacuum.
Highlights
The Standard Model (SM) is well established to describe the physics below the weak scale, and the SM particle content is complete after the discovery of the Higgs boson whose mass is 125 GeV
More than one pair can be made light as well. We consider such a scenario and show that both problems can be solved, i.e., (i) Yukawa unification and (ii) less fine tuning in little hierarchy can be achieved in the context of 4 Higgs doublet (4HD) SUSY models arising from SO(10) or SU(5)
We find that the renormalization group equation (RGE) running of the top, bottom and tau Yukawa couplings for cos ζu ≃ 1, tan ζd ∼ 1 and tan β ∼ 30 resembles the running in minimal supersymmetric standard model (MSSM) for tan β ≃ 50
Summary
The Standard Model (SM) is well established to describe the physics below the weak scale, and the SM particle content is complete after the discovery of the Higgs boson whose mass is 125 GeV. QS is a dimensionful parameter while the smallness of Q0 compared to the Planck scale is due to dimensionless parameters The closeness of these two unrelated scales defines the fine tuning of the little hierarchy which is elevating with the non-observation of SUSY particles [11, 12, 13, 14, 15, 16]. More than one pair can be made light as well We consider such a scenario and show that both problems can be solved, i.e., (i) Yukawa unification and (ii) less fine tuning in little hierarchy can be achieved in the context of 4 Higgs doublet (4HD) SUSY models arising from SO(10) or SU(5).
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