Browsing by Author "Leontaris, George K."
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Item Non-minimal quartic inflation in supersymmetric SO(10)(Elsevier Science, 2016-12-16) Leontaris, George K.; Okada, Nobuchika; Shafi, Qaisar; George K. Leontaris, Nobuchika Okada, Qaisar Shafi; Shafi, QaisarWe describe how quartic (λφ4) inflation with non-minimal coupling to gravity is realized in realistic supersymmetric SO(10)models. In a well-motivated example the 16 −16Higgs multiplets, which break SO(10)to SU(5)and yield masses for the right-handed neutrinos, provide the inflaton field φ. Thus, leptogenesis is a natural outcome in this class of SO(10)models. Moreover, the adjoint (45-plet) Higgs also acquires a GUT scale value during inflation so that the monopole problem is evaded. The scalar spectral index nsis in good agreement with the observations and r, the tensor to scalar ratio, is predicted for realistic values of GUT parameters to be of order 10−3–10−2.Item Smooth hybrid inflation with low reheat temperature and observable gravity waves in SU(5) × U(1)χ super-GUT(Journal of Cosmology and Astroparticle Physics, 2022-06-23) Ahmed, Waqas; Karozas, Athanasios; Leontaris, George K.; Zubair, UmerWe realize smooth hybrid inflation in the framework of supersymmetric SU(5) × U(1)χ ⊂ SO(10) model which provides a natural solution to the monopole problem appearing in the spontaneous symmetry breaking of SU(5). The breaking of U(1)χ symmetry leaves a residual discrete Z2 symmetry, that serves as the MSSM matter parity, realizing the possibility of the lightest supersymmetric particle as a cold dark matter candidate. The d = 5 proton lifetime for the decay p ⟶ K+ν̅, mediated by color-triplet Higgsinos is found to satisfy current experimental bounds if split-high scale SUSY scenario is employed. We show that with minimal Kähler potential, the soft supersymmetry breaking terms play a vital rôle in bringing the scalar spectral index ns within the Planck's latest bounds. In a minimal Kähler potential setup, small values of tensor-to-scalar ratio r ≲ 3.5 × 10-7 are obtained, whereas the gravitino mass turns out to be in the range that favors PeV scale SUSY but is not sufficiently high to avoid the d = 5 proton decay. A non-minimal Kähler potential including higher order corrections is required to realize successful inflation with central value of scalar spectral index ns = 0.9655, large tensor modes r ≲ 0.056 and a low reheat temperature (3 × 106 ≲ Tr ≲ 6.5 × 107) GeV consistent with leptogenesis and baryogenesis.