Smooth μ-hybrid and non-minimal Higgs inflation in SU(4) _C × SU(2)_L × SU(2)_R with observable gravitational waves

Abstract We propose to study a smooth variant of the μ -hybrid inflation model and a non-minimal Higgs model of inflation with quartic non-minimal coupling between the Higgs field and gravity within the context of a realistic GUT gauge group based on supersymmetric SU(4) C × SU(2) L × SU(2) R . These models are incorporated with a realistic scenario of reheating and non-thermal leptogenesis, compatible with the constraints from the baryon asymmetry of the universe. Notably, both models successfully address the MSSM μ -problem and avoid the issue of primordial magnetic monopoles. Our analysis reveals that both models predict a scalar spectral index n s that closely aligns with the central observationally favored value of Planck2018 + BICEP2/Keck Array (BK15) data and yield a large tensor-to-scalar ratio ( r > 10 -3 ), potentially detectable in forthcoming CMB experiments.