Revisiting CMB constraints on Warm Inflation

TL;DR

This paper reanalyzes Planck 2015 data to constrain warm inflation parameters, demonstrating that observational data can effectively limit theoretical models involving a scalar field with self-interaction and dissipation.

Contribution

It provides new constraints on warm inflation parameters using a comprehensive MCMC analysis of Planck data, highlighting parameter degeneracies and the potential for observational constraints.

Findings

Constraints on inflaton self coupling $bb$ and dissipation parameter $Q_P$ derived.

Degeneracy between $bb$ and $Q_P$ identified in the parameter space.

Warm inflation parameters can be effectively constrained with current CMB data.

Abstract

We revisit the constraints that Planck 2015 temperature, polarization and lensing data impose on the parameters of warm inflation. To this end, we study warm inflation driven by a single scalar field with a quartic self interaction potential in the weak dissipative regime. We analyse the effect of the parameters of warm inflation, namely, the inflaton self coupling $\lambda$ and the inflaton dissipation parameter $Q_P$ on the CMB angular power spectrum. We constrain $\lambda$ and $Q_P$ for 50 and 60 number of e-foldings with the full Planck 2015 data (TT, TE, EE + lowP and lensing) by performing a Markov-Chain Monte Carlo analysis using the publicly available code {\tt CosmoMC} and obtain the joint as well as marginalized distributions of those parameters. We present our results in the form of mean and 68 \% confidence limits on the parameters and also highlight the degeneracy between $\lambda$ and $Q_P$ in our analysis. From this analysis we show how warm inflation parameters can be well constrained using the Planck 2015 data.