Search

We study a renormalizable supersymmetric (SUSY) |$SO(10)$| grand unified theory model where the Yukawa couplings of single |${\bf 10}$|⁠ , single |${\bf \overline{126}}$|⁠ , and single |${\bf 120}$| fields (⁠|$Y_{10}$|⁠ , |$Y_{126}$|⁠ , and |$Y_{120}$|⁠) account for the quark and lepton Yukawa couplings and the neutrino mass. We pursue the possibility that |$Y_{10}$|⁠ , |$Y_{126}$|⁠ , and |$Y_{120}$| reproduce the correct quark and lepton masses, Cabibbo–Kobayashi–Maskawa and Pontecorvo–Maki–Nakagawa–Sakata (PMNS) matrices and neutrino mass differences, and at the same time suppress dimension-5 proton decays (proton decays via colored Higgsino exchange) through their texture, so that the soft SUSY-breaking scale can be reduced as much as possible without conflicting the current experimental bound on proton decays. We perform a numerical search for such a texture, and investigate implications of that texture on unknown neutrino parameters, the Dirac CP phase of the PMNS matrix, the lightest neutrino mass, and the |$(1,1)$| -component of the neutrino mass matrix in the charged lepton basis. Here we concentrate on the case when the active neutrino mass is generated mostly by the Type-2 seesaw mechanism, in which case we can obtain predictions for the neutrino parameters from the condition that dimension-5 proton decays be suppressed as much as possible. [ABSTRACT FROM AUTHOR]

In the minimal SUSY SU(5) GUT with O(1) TeV SUSY particles and O(1) or below self-coupling for the GUT-breaking Higgs field, the width of the dimension-6 proton decay is suppressed below the reach of Hyper-Kamiokande. In this paper, we point out that a SUSY SO(10) GUT which adopts only 4 5 H + 1 6 H + 16 ¯ H GUT-breaking Higgs fields leads to an enhanced dimension-6 proton decay width detectable at Hyper-Kamiokande. The enhancement is because the SU(5)-breaking VEV of 45H arises due to Planck-suppressed terms, W ∝ (45H2)2/M∗ + 45H4/M∗, and is therefore substantially larger than the other VEVs that conserve SU(5). As a result, the (3,2, 1/6) GUT gauge boson mass is about 1/5 smaller than the (3,2, −5/6) GUT gauge boson mass and can induce a fast dimension-6 proton decay. Through a numerical analysis on threshold corrections of the GUT gauge bosons and the physical components of the GUT-breaking Higgs fields, we confirm that the dimension-6 proton decay can be within the reach of Hyper-Kamiokande. [ABSTRACT FROM AUTHOR]