On the viability of quintessential inflationary models from observational data

TL;DR

This paper evaluates the viability of quintessential inflation models using observational data, emphasizing the importance of considering models with non-zero running of the spectral index and challenging the standard low e-folds assumption.

Contribution

It introduces a comprehensive analysis of quintessential inflation models accounting for non-zero running, expanding the set of viable inflationary potentials beyond traditional constraints.

Findings

Quartic and Higgs potentials are compatible with observational data when running is considered.

Models with 50-60 e-folds lying outside 95.5% confidence are not necessarily ruled out.

Accounting for running broadens the class of viable inflationary models.

Abstract

Assuming that primordial density fluctuationas are nearly Gaussian, from a frequentist viewpoint, the two-dimensional marginalized joint coincidence contour in the plane $(n_s,r)$ (being $n_s$ the spectral index and $r$ the ratio of tensor to scalar perturbations), without the presence of running is usually used to test the viability of the inflationary models. The models that provide, between $50$ and $60$ e-folds, a curve in that plane, which lies outside the $95.5 \%$ C.L are ruled out. I will basically argue that the this low number of e-folds is unjustified, and that models leading to a theoretical value of the running different from zero must be checked with observational data allowing the running. When both prescriptions are taken into account, dealing in the context of quintessential inflation, i.e. when the potential is a combination of an inflationary with a quintessential one that leads to a deflationary regime, inflationary models such as the quartic or the Higgs potential are allowed.