In ation in Supersymmetric SU(5) and Flipped SU(5) Models

Abstract

We have studied new inflation, nonminimal Higgs inflation and standard hybrid in flation in supersymmetric SU(5) and flipped SU(5) GUT groups. We have employed power-law form of K¨ahler potential for new inflation and special/log-form for nonmin imal Higgs inflation and standard hybrid inflation. The predictions of all these models are compared with Planck’s 2018 data and the results are found in perfect agreement. We have explored the regions of our parametric space which lie within Planck’s one sigma and two-sigma bounds on scalar spectral index ns. New inflation and standard hybrid inflation models are small field models and the value of tensor-to-scalar ratio 10−14 . r . 10−8 and running of scalar spectral index 10−9 . |dns/d ln k| . 10−3 is quite small in these models, on the other hand in nonminimal Higgs inflation model field values are large and the value of r turns out to be of the order of r ∼ 10−3 . Role of U(1)R symmetry and Zn symmetry is also studied and their impact on the analytical and numerical calculations have been discussed. These symmetries play an impor tant role in suppressing fast proton decay. Problem of gauge coupling unification in R-symmetric SU(5) is solved by assuming extra vector like families and for gener ating right-handed neutrino masses in R-symmetric flipped SU(5) we have assumed R-symmetry breaking at renormalizable level. In nonminimal model Zn symmetry is restricted with n ≤ 4 to fulfill the requirement of sub-Planckian field values. Fur thermore, reheating with successful leptogenesis is realized in these models. Reheat temperatures Tr in our models varies from 106 − 1010 GeV.