Revisiting CMB constraints on warm inflation

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 λ and the inflaton dissipation parameter Q P on the CMB angular power spectrum. We constrain λ 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 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 λ and Q P in our analysis. From this analysis we show how warm inflation parameters can be well constrained using the Planck 2015 data.

Adiabatic out-of-equilibrium solutions to the Boltzmann equation in warm inflation

“…In particular, for weak dissipation at horizon-crossing, predictions for n s and r differ significantly for the limiting cases where inflaton fluctuations are in a vacuum or in a thermal state (i.e., in equilibrium with the overall thermal bath) [17,19]. Although for strong dissipation this issue becomes less relevant, since dissipation becomes the dominant source of inflaton fluctuations, agreement with observations in most scenarios considered so far typically favours the Q * 1 regime [17,19,[48][49][50]. The dissipative dynamics itself is not sufficient to determine the state of inflaton fluctuations, since other processes in the thermal bath can be responsible for a substantial creation and annihilation of inflaton particles.…”

Identifying universality in warm inflation

“…Recently a first principles warm inflation model was constructed from QFT which involves just a few fields [27], thus convincingly demonstrating that warm inflation models are on an equal footing to cold inflation as model building prospects. Moreover, the dissipative effects and the presence of a non-vanishing radiation bath are able to change both the inflationary dynamics at the background and at the fluctuation levels [29][30][31][32][33][34][35][36][37], such that there can be distinctive differences between the two paradigms which could be testable. As such, it is useful to understand the dynamical structure of warm inflation through different perspectives, which is a motivation of this paper.…”

Observational constraints on warm inflation in loop quantum cosmology

“…3 Our strategy is similar to what was used previously in ref [35][68,69],. but with analogous results to the first one.…”