Using gauge coupling unification and proton decay to test minimal supersymmetric SU (5)

Advances in High Energy Physics, 2018

Nonsupersymmetric minimal SU(5) with Higgs representations 24 퐻 and 5 퐻 and standard fermions in 5 퐹 ⊕ 10 퐹 is well known for its failure in unification of gauge couplings and lack of predicting neutrino masses. Like standard model, it is also affected by the instability of the Higgs scalar potential. We note that extending the Higgs sector by 75 퐻 and 15 퐻 not only leads to the popular type-II seesaw ansatz for neutrino masses with a lower bound on the triplet mass Δ > 2 × 10 9 GeV, but also achieves precision unification of gauge couplings without proliferation of nonstandard light Higgs scalars or fermions near the TeV scale. Consistent with recent LUX-2016 lower bound, the model easily accommodates a singlet scalar WIMP dark matter near the TeV scale which resolves the vacuum stability issue even after inclusion of heavy triplet threshold effect. We estimate proton lifetime predictions for → + 0 including uncertainties due to input parameters and threshold effects due to superheavy Higgs scalars and superheavy ±4/3 , ±1/3 gauge bosons. The predicted lifetime is noted to be verifiable at Super Kamiokande and Hyper Kamiokande experiments.

Progress of Theoretical Physics, 1997

Dimension-five operators for nucleon decays are suppressed in the modified missing doublet (MMD) model in the supersymmetric SU(5) grand unification. We show that nonrenormalizable interactions decrease the unification scale in the MMD model which increases the nucleon decay rate of dimensionsix operators by a significant amount. We find that the theoretical lower bound on the proton life time τ (p → e + π 0) is within the observable range at SuperKamiokande.

Physical Review D, 2008

The unification of gauge interactions in the context of Adjoint SU(5) and its phenomenological consequences are investigated. We show the allowed mass spectrum of the theory which is compatible with proton decay, and discuss the possibility to have a cold dark matter candidate. Due to the upper bounds on the proton decay partial lifetimes, τ (p → K +ν) ≤ 9.3×10 36 years and τ (p → π +ν) ≤ 3.0 × 10 35 years, the theory could be tested at future proton decay experiments. The theory predicts also light scalar color octets which could be produced at the Large Hadron Collider.

Nuclear Physics B, 1992

We confront the precise LEP determinations of SIn 2OW and the strong coupling 0 3(mz) with the predictions of the minimal supersymmetric SU(5) GUT. We incorporate O(0cm03) effects in the extraction of sin 2O~from LEP data. We incorporate distinct thresholds for the supersymmetric partners of the different species of Standard Model particles, parameterized in terms of a scalar mass m 0 and a gaugino mass m1/2 that are assumed to be universal at the GUT scale. We also allow for uncertainties in the top, higgs and higgsino masses. We use the full two-loop renormalization group equations including top, bottom and tau Yukawa couplings. We show that GUT threshold effects are small because proton stability prevents triplet Higgs particles from weighing much less than 1016 GeV. Using 1-u errors for the experimental inputs and plausible ranges for unknown supersymmetric model parameters, in particular an upper bound of 300 GeV on the higgs mixing parameter~z, we find that either 3.0x 1012 TeV> m1/2>21 TeV or 011/2 <65 GeV, with the intermediate range allowed at the 2-u level. An upper bound of = 500 GeV excludes 011/2 from 80 GeV to 5 TeV at 1-u, and an upper bound of~z= I TeV excludes m1/2 from 110 GeV to 620 GeV at 1o. It is not possible at present to fix the supersymmetry breaking scale with any precision.

Physics Letters B, 2007

We investigate the unification constraints in the minimal sypersymmetric grand unified theories based on SU (5) gauge symmetry. The most general constraints on the spectrum of minimal supersymmetric SU (5) and flipped SU (5) are shown. The upper bound on the mass of the colored Higgs mediating proton decay is discussed in detail in the context of the minimal supersymmetric SU (5). In the case of the minimal SUSY SU (5) we show that if we stick to the strongest bound on the colored triplet mass coming from dimension five proton decay contributions there is no hope to test this model at future nucleon decay experiments through the dimension six operators. We find a lower bound on the partial proton decay lifetime for all relevant channels in the context of flipped SUSY SU (5). We conclude that flipped SUSY SU (5) might be in trouble if proton decay is found at the next generation of experiments with a lifetime below 10 37 years.

Journal of High Energy Physics, 2021

We explore proton decay in a class of realistic supersymmetric flipped SU(5) models supplemented by a U(1)R symmetry which plays an essential role in implementing hybrid inflation. Two distinct neutrino mass models, based on inverse seesaw and type I seesaw, are identified, with the latter arising from the breaking of U(1)R by nonrenormalizable superpotential terms. Depending on the neutrino mass model an appropriate set of intermediate scale color triplets from the Higgs superfields play a key role in proton decay channels that include p → (e+, μ+) π0, p → (e+, μ+) K0, p →$$ \overline{v}{\pi}^{+} $$ v ¯ π + , and p →$$ \overline{v}{K}^{+} $$ v ¯ K + . We identify regions of the parameter space that yield proton lifetime estimates which are testable at Hyper-Kamiokande and other next generation experiments. We discuss how gauge coupling unification in the presence of intermediate scale particles is realized, and a Z4 symmetry is utilized to show how such intermediate scales can aris...

Journal of High Energy Physics, 2000

We construct and discuss a "realistic" example of SUSY SU(5) GUT model, with an additional U(1) flavour symmetry, that is not plagued by the need of large fine tunings, like those associated with doublet-triplet splitting in the minimal model, and that leads to an acceptable phenomenology. This includes coupling unification with a value of α s (m Z ) in much better agreement with the data than in the minimal version, an acceptable hierarchical pattern for fermion masses and mixing angles, also including neutrino masses and mixings, and a proton decay rate compatible with present limits (but the discovery of proton decay should be within reach of the next generation of experiments). In the neutrino sector the preferred solution is one with nearly maximal mixing both for atmospheric and solar neutrinos.

Physics Letters B, 1994

Physics Letters B, 1984

Physics Letters B, 1990