Likelihood analysis of small field polynomial models of inflation yielding a high Tensor-to-Scalar ratio

TL;DR

This paper analyzes polynomial inflationary models with Planckian field excursions, solving the equations exactly and identifying models that produce a high tensor-to-scalar ratio consistent with CMB data, highlighting inter-dependencies among observables.

Contribution

It introduces a probabilistic and fitting approach to identify the most likely polynomial inflation models that yield a high tensor-to-scalar ratio and explores their observable inter-dependencies.

Findings

Identified models with r=0.01 compatible with CMB data

Found significant inter-dependencies among CMB observables

Provided exact solutions to Mukhanov-Sasaki equations for polynomial potentials

Abstract

Inflationary potentials, with Planckian field excursions, described by a 6th degree polynomial are studied. We solve the Mukhanov-Sasaki equations exactly and employ a probabilistic approach as well as multinomial fitting to analyse the results. We identify the most likely models which yield a tensor-to-scalar ratio $r=0.01$ in addition to currently allowed Cosmic Microwave Background (CMB) spectrum and observables. Additionally, we find a significant inter-dependence of CMB observables in these models. This might be an important effect for future analyses, since the different moments of the primordial power spectrum are taken to be independent in the usual Markov chain Monte Carlo methods.