Dynamical and observational constraints on the Warm Little Inflaton scenario

TL;DR

This paper investigates the Warm Little Inflaton scenario, analyzing its dynamics and observational predictions across different potentials, and finds it consistent with Planck data for a broad parameter range.

Contribution

It provides a comprehensive analysis of the Warm Little Inflaton scenario with various potentials, including thermal effects and observational constraints, demonstrating its viability.

Findings

The scenario remains consistent with 50-60 e-folds of inflation.

Predicted scalar spectra and tensor-to-scalar ratios align with Planck data.

The model is viable across a broad parameter space.

Abstract

We explore the dynamics and observational predictions of the Warm Little Inflaton scenario, presently the simplest realization of warm inflation within a concrete quantum field theory construction. We consider three distinct types of scalar potentials for the inflaton, namely chaotic inflation with a quartic monomial potential, a Higgs-like symmetry breaking potential and a non-renormalizable plateau-like potential. In each case, we determine the parametric regimes in which the dynamical evolution is consistent for 50-60 e-folds of inflation, taking into account thermal corrections to the scalar potential and requiring, in particular, that the two fermions coupled directly to the inflaton remain relativistic and close to thermal equilibrium throughout the slow-roll regime and that the temperature is always below the underlying gauge symmetry breaking scale. We then compute the properties of the primordial spectrum of scalar curvature perturbations and the tensor-to-scalar ratio in the allowed parametric regions and compare them with Planck data, showing that this scenario is theoretically and observationally successful for a broad range of parameter values.