Quasi-pole inflation in metric-affine gravity

TL;DR

This paper introduces a novel inflationary mechanism within metric-affine gravity, where a non-minimally coupled inflaton with a steep coupling function creates an exponential plateau, mimicking Starobinsky inflation.

Contribution

It presents a new inflation model leveraging quasi-pole behavior in the inflaton kinetic function induced by non-minimal coupling to the Holst invariant.

Findings

Inflationary predictions match Starobinsky inflation.

The kinetic function develops a quasi-pole near the zero of the coupling.

The potential features an exponential plateau regardless of the original shape.

Abstract

We propose a new mechanism for inflationary model building in the framework of metric-affine gravity. Such a mechanism involves an inflaton non-minimally coupled with the Holst invariant. If the non-minimal coupling function has a zero point and it is very steep at that same point, the corresponding inflaton kinetic function will feature a quasi-pole behaviour, implying a canonically normalized potential featuring an exponential plateau, regardless of the shape of the original inflaton potential. The inflationary predictions in such a region are equivalent to the ones of Starobinsky inflation.