Abstract
We propose a simple non-supersymmetric grand unified theory (GUT) based on the gauge group SO(10) times U(1)_psi . The model includes 3 generations of fermions in mathbf{16} (+1), mathbf{10} (-2) and mathbf{1} (+4) representations. The mathbf{16}-plets contain Standard Model (SM) fermions plus right-handed neutrinos, and the mathbf{10}-plet and the singlet fermions are introduced to make the model anomaly-free. Gauge coupling unification at M_{GUT} simeq 5 times 10^{15}{-}10^{16} GeV is achieved by including an intermediate Pati–Salam breaking at M_{I} simeq 10^{12}{-}10^{11} GeV, which is a natural scale for the seesaw mechanism. For M_{I} simeq 10^{12}{-}10^{11}, proton decay will be tested by the Hyper-Kamiokande experiment. The extra fermions acquire their masses from U(1)_psi symmetry breaking, and a U(1)_psi Higgs field drives a successful inflection-point inflation with a low Hubble parameter during inflation, H_{inf} ll M_{I}. Hence, cosmologically dangerous monopoles produced from SO(10) and PS breakings are diluted away. This is the first SO(10) model we are aware of in which relatively light intermediate mass (sim 10^{10}{-}10^{12} GeV) primordial monopoles can be adequately suppressed. The reheating temperature after inflation can be high enough for successful leptogenesis. With the Higgs field contents of our model, a mathbf{Z}_2 symmetry remains unbroken after GUT symmetry breaking, and the lightest mass eigenstate among linear combinations of the mathbf{10}-plet and the singlet fermions serves as a Higgs-portal dark matter (DM). We identify the parameter regions to reproduce the observed DM relic density while satisfying the current constraint from the direct DM detection experiments. The present allowed region will be fully covered by the future direct detection experiments such as LUX-ZEPLIN DM experiment. In the presence of the extra fermions, the SM Higgs potential is stabilized up to M_{I}.
Highlights
The lure of Grand Unified Theories (GUTs) is that the Standard Model (SM) gauge symmetry, SU (3)c × SU (2)L × U (1)Y, is unified into a single gauge group, so that the three SM gauge interactions originate from a single theory.the SM quarks and leptons are unified into certain representations of the grand unified theory (GUT) gauge group, leading to the quantization of their electric charges [1,2,3]
Supersymmetric (SUSY) GUT models have been commonly studied in the literature, motivated by the fact that three SM gauge couplings are successfully unified at the GUT scale MGU T : αL (MGU T) 1016
We have proposed a simple non-supersymmetric GUT model based on the gauge group S O(10) × U (1)ψ
Summary
The lure of Grand Unified Theories (GUTs) is that the Standard Model (SM) gauge symmetry, SU (3)c × SU (2)L × U (1)Y , is unified into a single gauge group, so that the three SM gauge interactions originate from a single theory. The U (1)ψ symmetry is broken at the intermediate scale by the vacuum expectation value (VEV) of a S O(10) singlet Higgs field This field is identified with the inflaton field which drives the IPI inflation in our model, such that all monopoles associated with the GUT and the PS SSBs are adequately diluted. All the Higgs representations are Z2-even, the Z2 symmetry remains unbroken even after the SSB down to the SM [54], and as a result the lightest mass eigenstate among electrically neutral components in the new 10-plet and singlet fermions serves as a dark matter (DM) in our universe (for an axion DM scenario in the context of S O(10) models, see, for example, Refs. The U (1)ψ gauge symmetry is crucial for a successful IPI scenario, where the S O(10) singlet Higgs field A is identified with the inflaton
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
