Starobinsky-Type Inflation With Products of Kaehler Manifolds

We present a novel realization of Starobinsky-type inflation within Supergravity using two chiral superfields. The proposed superpotential is inspired by induced-gravity models. The Kaehler potential contains two logarithmic terms, one for the inflaton T and one for the matter-like field S, parameterizing the SU(1,1)/U(1)x SU(2)/U(1) Kaehler manifold. The two factors have constant curvatures -m/n and 2/n2, where n, m are the exponents of T in the superpotential and Kaehler potential respectively, and 0<n2<=6. The inflationary observables depend on the ratio 2n/m only. Essentially they coincide with the observables of the original Starobinsky model. Moreover, the inflaton mass is predicted to be 3x10^13 GeV.