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.
Highlights
We may utilize a nilpotent superfield S [21], or a matter field S charged under a gauged R-symmetry [19].We propose a new solution to the stability problem that is compatible with a highly symmetric Kahler manifold
The Kahler potential involves a logarithmic function of the inflaton field T with an overall negative prefactor, as required for establishing an asymptotic inflationary plateau [7,8,9,10]
This model of inflation preserves a number of attractive features: (i) The superpotential and the Kahler potential may be fixed in the presence of an R-symmetry and a discrete symmetry; (ii) the initial value of the inflaton field can be subplanckian; (iii) the radiative corrections remain under control; and (iv) the perturbative unitarity is respected up to the reduced Planck scale [10, 26, 28, 29]
Summary
We may utilize a nilpotent superfield S [21], or a matter field S charged under a gauged R-symmetry [19]. Compactification manifold contains a spherical SU (2)/U (1) factor, this must be supported by suitable 2-form flux, which might affect the brane worldvolume theory Given this discussion, it may be difficult to realize a situation in which the field configuration manifold is globally isomorphic to the symmetric product space SU (1, 1)/U (1) × SU (2)/U (1) in the context of string inflationary models. We show that imposing a simple asymptotic condition on n, m and n11, a Starobinsky-type inflationary potential gets generated, exhibiting an attractor behavior that depends only on the coefficient n11, which determines the curvature of the SU (1, 1)/U (1) Kahler manifold This model of inflation preserves a number of attractive features: (i) The superpotential and the Kahler potential may be fixed in the presence of an R-symmetry and a discrete symmetry; (ii) the initial value of the (noncanonically normalized) inflaton field can be subplanckian; (iii) the radiative corrections remain under control; and (iv) the perturbative unitarity is respected up to the reduced Planck scale [10, 26, 28, 29].
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