Scalar-tensor linear inflation

TL;DR

This paper explores two approaches to non-minimally coupled gravity theories that produce linear inflation as an attractor, focusing on scalar-tensor theories and particle physics motivated potentials, revealing modifications of induced inflation.

Contribution

It introduces two methods to realize linear inflation as an attractor in non-minimal gravity theories, connecting scalar-tensor and particle physics perspectives.

Findings

Both approaches yield Jordan frame potentials that lead to linear inflation in the strong coupling limit.

The scalar-tensor approach restores linear inflation results for various non-minimal couplings.

Loop corrections motivate the form of the Jordan frame potential in the particle physics approach.

Abstract

We investigate two approaches to non minimally coupled gravity theories which present linear inflation as attractor solution: a) the scalar-tensor theory approach, where we look for a scalar-tensor theory that would restore results of linear inflation in the strong coupling limit for any form of the non-minimal coupling to gravity of the form of $f(\varphi)R/2$; b) the particle physics approach, where we motivate the form of the Jordan frame potential by the loop corrections to the inflaton field. In both cases the Jordan frame potentials are modifications of the induced inflation, but instead of the Starobinsky attractor they lead to the linear inflation in the strong coupling limit.