Starobinsky-type inflation with products of Kähler manifolds

Abstract

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 Kähler 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) × SU(2)/U(1) Kähler manifold. The two factors have constant curvatures -m/n and 2/n2, where n, m are the exponents of T in the superpotential and Kähler 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 3·1013 GeV.