Starobinsky Inflation: From Non-SUSY to SUGRA Realizations

We review the realization of Starobinsky-type inflation within induced-gravity Supersymmetric (SUSY) and non-SUSY models. In both cases, inflation is in agreement with the current data and can be attained for subplanckian values of the inflaton. The corresponding effective theories retain perturbative unitarity up to the Planck scale and the inflaton mass is predicted to be 3x10^13 GeV. The supergravity embedding of these models is achieved by employing two gauge singlet chiral supefields, a superpotential that is uniquely determined by a continuous R and a discrete Zn symmetry, and several (semi)logarithmic Kaehler potentials that respect these symmetries. Checking various functional forms for the non-inflaton accompanying field in the Kaehler potentials, we identify four cases which stabilize it without invoking higher order terms.
Comment: Title changed and references added; to appear in Adv. High Energy Phys