Higgs as a Probe of Supersymmetric Grand Unification with the Hosotani Mechanism

The supersymmetric grand unified theory where the SU(5) gauge symmetry is broken by the Hosotani mechanism predicts the existence of adjoint chiral superfields whose masses are at the supersymmetry breaking scale. The Higgs sector is extended with the SU(2)_L triplet with hypercharge zero and neutral singlet chiral multiplets from that in the minimal supersymmetric standard model. Since the triplet and singlet chiral multiplets originate from a higher-dimensional vector multiplet, this model is highly predictive. Properties of the particles in the Higgs sector are characteristic and can be different from those in the Standard Model and other models. We evaluate deviations in coupling constants of the standard model-like Higgs boson and the mass spectrum of the additional Higgs bosons. We find that our model is discriminative from the others by precision measurements of these coupling constants and masses of the additional Higgs bosons. This model can be a good example of grand unification that is testable at future collider experiments such as the luminosity up-graded Large Hadron Collider and future electron-positron colliders.