Unitarizing non-Minimal Inflation via a Linear Contribution to the Frame Function

We show that non-minimal inflation, based on the phi^4 potential, may be rendered unitarity conserving and compatible with the Planck results for 4.6x10^(-3)<~r21=c2R/c1R^2<~1, if we introduce a linear contribution (c1R phi) to the frame function which takes the form fR=1+c1R phi+c2R phi^2. Supersymmetrization of this model can be achieved by considering two gauge singlet superfields and combining a linear-quadratic superpotential term, with a class of logarithmic or semi-logarithmic Kaehler potentials with prefactor for the logarithms including the inflaton field -(2n+3) or -2(n+1) where -0.01<~ n<~0.013.Comment: Published Version. arXiv admin note: text overlap with arXiv:1807.0115

Kinetically Modified Non-Minimal Inflation With Exponential Frame Function

We consider Supersymmetric (SUSY) and non-SUSY models of chaotic inflation based on the phi^n potential with n=2 or 4. We show that the coexistence of an exponential nonminimal coupling to gravity, fR=Exp(cR phi^p), with a kinetic mixing of the form fK=cK fR^m can accommodate inflationary observables favored by the Planck and Bicep2/Keck Array results for p=1 and 2, 1<=m<=15 and 2.6x10^(-3)<=rRK=cR/cK^(p/2)<=1, where the upper limit is not imposed for p=1. Inflation is of hilltop type and it can be attained for subplanckian inflaton values with the corresponding effective theories retaining the perturbative unitarity up to the Planck scale. The supergravity embedding of these models is achieved employing two chiral gauge singlet supefields, a monomial superpotential and several (semi)logarithmic or semipolynomial Kaehler potentials.Comment: Minor revisions have been made; to appear in EPJ

Induced-Gravity Inflation in no-Scale Supergravity and Beyond

Supersymmetric versions of induced-gravity inflation are formulated within Supergravity (SUGRA) employing two gauge singlet chiral superfields. The proposed superpotential is uniquely determined by applying a continuous R and a discrete Z_n symmetry. We select two types of logarithmic Kahler potentials, one associated with a no-scale-type SU(2,1) / SU(2) x U(1)_R x Z_n Kahler manifold and one more generic. In both cases, imposing a lower bound on the parameter cR involved in the coupling between the inflaton and the Ricci scalar curvature - e.g. cR > 76, 105, 310 for n=2,3 and 6 respectively -, inflation can be attained even for subplanckian values of the inflaton while the corresponding effective theory respects the perturbative unitarity. In the case of no-scale SUGRA we show that, for every n, the inflationary observables remain unchanged and in agreement with the current data while the inflaton mass is predicted to be 3x10^13 GeV. Beyond no-scale SUGRA the inflationary observables depend mildly on n and crucially on the coefficient involved in the fourth order term of the Kahler potential which mixes the inflaton with the accompanying non-inflaton field.Comment: Final versio