Inflation and nonequilibrium thermodynamics for the fluctuations in the infrared sector

TL;DR

This paper explores the nonequilibrium thermodynamics of matter field fluctuations during inflation, revealing negative heat capacity and exponential growth of states in the infrared sector for different universe expansion models.

Contribution

It introduces a thermodynamic framework for analyzing matter fluctuations in inflationary cosmology, highlighting the growth of states and the role of effective temperature at horizon entry.

Findings

Negative heat capacity in both de Sitter and power-law expansions

Exponential and superexponential growth of states in the infrared sector

Fluctuation spectrum linked to background effective temperature

Abstract

In the framework of inflationary cosmology I study some aspects of nonequilibrium thermodynamics for the matter field fluctuations. The thermodynamic analysis is developed for de Sitter and power - law expansions of the universe. In both cases, I find that the heat capacity is negative leading respectively, to exponential and superexponential growth for the number of states in the infrared sector for de Sitter and power-law expansions of the universe. The spectrum for the matter field fluctuations can be understood from the background effective temperature when the horizon entry.