Unification in 5D SO(10)

Abstract

Gauge unification in a five dimensional supersymmetric SO(10) model compactified on an orbifold S 1 /(Z 2 × Z ′ 2 ) is studied. One orbifolding reduces N = 2 supersymmetry to N = 1, and the other breaks SO(10) to the Pati-Salam gauge group SU(4) C × SU(2) L × SU(2) R . Further breaking to the standard model gauge group is made through the Higgs mechanism on one of the branes. The differences of the three gauge couplings run logarithmically even in five dimensions and we can keep the predictability for unification as in four dimensional gauge theories. We obtain an excellent prediction for gauge coupling unification with a cutoff scale M * ∼ 3 × 10 17GeV and a compactification scale M c ∼ 1.5 × 10 14 GeV. Finally, although proton decay due to dimension 5 operators may be completely eliminated, the proton decay rate in these models is sensitive to the placement of matter multiplets in the 5th dimension, as well as to the unknown physics above the cutoff scale.

Search for nucleon decay into charged antilepton plus meson in Super-Kamiokande I and II

“…There are various viable GUTs (see, e.g., [6][7][8][9][10][11][12]), such as models incorporating supersymmetry (SUSY), models with a symmetry group like SO(10), flipped SU(5) models, and models in extra dimensions. Predictions for the lifetime of the nucleon strongly depend on the models and also have large uncertainties.…”

“…Many possibilities for nucleon decays are theoretically proposed. In some SU(5) and SO (10) GUT models ( [15][16][17][18]), branching ratios for p → e + η, p → e + ρ 0 or p → e + ω can be as high as 10 ∼ 20% and the proton and bound neutron lifetimes are expected to be comparable to each other. Also, N → µ + +meson modes can be induced by mixing effects between lepton families.…”

Erratum to “Neutrinos in a sterile throat” [Nucl. Phys. B 768 (2007) 157–176]

“…6 We calculate, in II C, the boundary conditions on the UV brane that follow from this interaction, and show that they lead to the presence of an ultralight mass eigenstate in the KK spectrum, of the deep throat, with the gauge hierarchy problem solved in some other way. 4 For related references, see [35,36,37,38,39,40,41,42,43,44]. 5 The co-ordinate z will always refer to the sterile throat in what follows.…”

Gauge coupling unification and SO(10) in 5D

“…In Sec. 2.3 we carefully analyse the effects of the Higgs mechanism, considering the models [1] and [2] already mentioned, denoting them as Pattern I and Pattern II respectively. For each of them we study all the possible values that can be assumed by the vacuum expectation value (VEV) of the Higgs field, focusing on two different regimes, that is high scale brane breaking (Case A) and brane breaking at an intermediate scale (Case B).…”