Abstract
We discuss proton decay in a recently proposed model of supersymmetric hybrid inflation based on the gauge symmetry SU(4)c× SU(2)L× SU(2)R. A U(1) R symmetry plays an essential role in realizing inflation as well as in eliminating some undesirable baryon number violating operators. Proton decay is primarily mediated by a variety of color triplets from chiral superfields, and it lies in the observable range for a range of intermediate scale masses for the triplets. The decay modes include p → e+(μ+) + π0, pto overline{nu}+{pi}^{+} , p → K0 + e+(μ+), and pto {K}^{+}+overline{nu} , with a lifetime estimate of order 1034–1036 yrs and accessible at Hyper-Kamiokande and future upgrades. The unification at the Grand Unified Theory (GUT) scale MGUT (∼ 1016 GeV) of the Minimal Supersymmetric Standard Model (MSSM) gauge couplings is briefly discussed.
Highlights
The Minimal Supersymmetric Standard Model (MSSM) matter superfields including right-handed neutrinos are contained in F and F c belonging to the following representations: Fi = (4, 2, 1) ≡
Proton decay is primarily mediated by a variety of color triplets from chiral superfields, and it lies in the observable range for a range of intermediate scale masses for the triplets
The various superfields with their representation, transformation under G4-2-2, decomposition under GSM, and respective charge q(R) are shown in table 1. It can be noted from the table 1 that the MSSM matter superfields F, F c carry one unit of R charge, while the MSSM Higgs doublets in h are neutral under the R symmetry
Summary
Which can lead to fast proton decay via the effective operator (v/Λ)2QL(uc)†(dc)†, suppressed by the color-triplet dc-squark mass. These operators are not allowed by the R symmetry defined in table 1. These interactions yield effective dimension-five proton decay operators via a chirality flipping propagator involving a mass insertion κ S HcHc = −m3/2HcHc, as shown in figure 1. Connecting external squark and/or slepton lines, in each of these dimension-five diagrams with a Higgsino or gaugino line one can generate oneloop (box) diagrams corresponding to LLLL and RRRR type four-Fermi proton decay operators. This value is rou√ghly comparable to the value obtained above from the dimension-five proton decay (i.e., ab 10−9)
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