6533b85efe1ef96bd12c0526

RESEARCH PRODUCT

Induced-Gravity Inflation in Supergravity Confronted with Planck2013 and BICEP2

subject

description

Supersymmetric versions of induced-gravity inflation are f ormulated within Super- gravity (SUGRA) employing two gauge singlet chiral superfie lds. The proposed superpotential is uniquely determined by applying a continuous R and a discrete Z2 symmetry. We also employ a logarithmic Kahler potential respecting the symmetries above and including all the allowed terms up to fourth order in powers of the various fields. When the Kahle r manifold exhibits a no-scale-type symmetry, the model predicts spectral index ns ≃ 0.963 and tensor-to-scalar r ≃ 0.004. Beyond no-scale SUGRA, ns and r depend crucially on the coefficient kSΦ involved in the fourth order term, which mixes the inflaton Φ with the accompanying non-inflaton superfield S in the Kahler potential, and the prefactor encountered in it. Increasing slightly the latter above (−3), an efficient enhancement of the resulting r can be achieved putting it in the observable range favored by the Planck and BICEP2/Keck Array results. In all cases, imposing a lower bound on the parameter cR, involved in the coupling between the inflaton and the Ricci s calar curvature, inflation can be attained for subplanckian values of the inflaton while the co rresponding effective theory respects the perturbative unitarity.