Gauss-Bonnet-coupled Quintessential Inflation

TL;DR

This paper introduces a new quintessential inflation model where the inflaton couples to the Gauss-Bonnet term, maintaining sub-Planckian field variation and aligning with observations without fine-tuning.

Contribution

The model uniquely couples the inflaton to the Gauss-Bonnet term, preventing fifth force issues and radiative corrections from disrupting the potential's flatness.

Findings

Inflationary predictions match CMB data.

Dark energy coincidence is achieved with natural parameters.

The model avoids fine-tuning of the cosmological constant.

Abstract

We study in detail a new model of quintessential inflation where the inflaton field is coupled to the Gauss-Bonnet term. This coupling ensures that the variation of the field is kept sub-Planckian, which avoids the 5th force problem as well as the lifting of the flatness of the quintessential tail in the runaway scalar potential due to radiative corrections. We find that the inflationary predictions of the model are in excellent agreement with CMB observations, while the coincidence requirement of dark energy is satisfied with natural values of the parameters, overcoming thereby the extreme fine-tuning of the cosmological constant in $\Lambda$CDM.