Abstract
We consider a cosmological inflation scenario based on a no-scale supergravity sector with $U(1)_R$ symmetry. It is shown that a tree level $U(1)_R$ symmetric superpotential alone does not lead to a slowly rolling scalar potential. A deformation of this tree level superpotential by including an explicit $R$ symmetry breaking term beyond the renomalizable level is proposed. The resulting potential is found to be similar (but not exactly the same) to the one in Starobinsky inflation model. We emphasize that for successful inflation, with the scalar spectral index $n_s \sim 0.96$ and the tensor-to-scalar ratio $r < 0.08$, a correlation between the mass parameters in the superpotential and the vacuum expectation value of the modulus field $T$ in the K\"ahler potential must be adopted.
Highlights
Planck satellite’s four year data of the cosmic microwave background radiation and the large structure in the Universe support the predictions of cosmological inflation
We propose a global R symmetry motivated inflation model within no-scale SUGRA
We find that the minimal Uð1ÞR symmetric superpotential is unable to provide a successful inflation, as the associated scalar potential turns out to be extremely steep
Summary
Planck satellite’s four year data of the cosmic microwave background radiation and the large structure in the Universe support the predictions of cosmological inflation. We propose a deformation of this tree level superpotential (having R charge 2) by including an explicit R symmetry breaking term beyond the renormalizable level. This new term is naturally expected to be suppressed by the cutoff scale MÃ, and W can be expressed as μS2. A similar MP suppressed R symmetry breaking term has been considered in a supersymmetric hybrid inflation scenario [22] with minimal Kähler potential.
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