The twilight of the single field slow rolling inflaton

TL;DR

This paper evaluates 49 slow roll inflationary potentials against PLANCK data, finding most disfavored by the running of the spectral index, but recent data improves viability, though the running of the running remains problematic.

Contribution

It provides a comprehensive analysis of multiple inflationary potentials using recent observational data, highlighting the impact of updated measurements on model viability.

Findings

Most potentials disfavored by PLANCK2013 data based on the running of the spectral index.

Recent PLANCK2015 data reduces the discrepancy, making most potentials viable.

The running of the running remains incompatible with theoretical predictions, disfavouring many models.

Abstract

We present an study from PLANCK2013+WP+BAO:$\Lambda$CDM+$r$+$\alpha_s$ data, where 49 slow roll inflationary potentials are tested, showing that the theoretical value of the running provided by 48 of these potentials has a deviation to the expected observational value larger than $1.6\sigma$, and its modulus is smaller than the modulus of the expected observational one, what disfavours these models at 94.5 \% of Confidence Level (C.L.), concluding from these results that, inflationary cosmology may require multiple fields or a breakdown of slow roll condition. This conclusion has drastically changed with the last data provided by PLANCK2015 where the modulus of the expected observational value of the running has been reduced one order, getting shorter the distance to its theoretical value $1\sigma$ or more, what allows the viability of the majority of the potentials disfavored by the running provided by PLANCK2013 data. However if one takes into account the running of the running, its theoretical value, which in the slow roll regime depends on the slow roll parameters at third order, is incompatible with the expected observational value provided by PLANCK2013 and PLANCK2015, disfavouring at 92.8 \% C.L. or more, 39 of the 49 slow roll potentials tested. Moreover, if one restricts the number of e-folds to be between 30 and 80, then only two potentials will survive to this test.