Density fluctuations from warm inflation

TL;DR

This paper derives new general results for the power spectrum of density fluctuations in warm inflation, especially when the friction coefficient depends on temperature, revealing significant amplitude increases.

Contribution

It provides the first comprehensive analysis of the power spectrum with temperature-dependent friction coefficients in warm inflation models.

Findings

Amplitude of perturbations increases with temperature-dependent friction.

New results for thermal fluctuations in the weak warm inflation regime.

Implications for model building in warm inflation scenarios.

Abstract

Thermal fluctuations provide the main source of large scale density perturbations in warm inflationary models of the early universe. For the first time, general results are obtained for the power spectrum in the case when the friction coefficient in the inflaton equation of motion depends on temperature. A large increase in the amplitude of perturbations occurs when the friction coefficient increases with temperature. This has to be taken into account when constructing models of warm inflation. New results are also given for the thermal fluctuations in the weak regime of warm inflation when the friction coefficient is relatively small.