Recent developments in warm inflation

TL;DR

This review covers recent advances in warm inflation, highlighting its distinct dynamics, particle physics models, and observational implications, contrasting it with cold inflation and addressing longstanding cosmological issues.

Contribution

It provides a comprehensive overview of warm inflation's theoretical models, quantum field theory foundations, and observational predictions, emphasizing its potential advantages over cold inflation.

Findings

Warm inflation models are less constrained by current data than cold inflation.

Dissipative effects can address issues like the swampland criteria.

Warm inflation offers viable parameter spaces for certain potentials.

Abstract

Warm inflation, its different particle physics model implementations and the implications of dissipative particle production for its cosmology are reviewed. First, we briefly present the background dynamics of warm inflation and contrast it with the cold inflation picture. An exposition of the space of parameters for different well-motivated potentials, which are ruled out, or severely constrained in the cold inflation scenario, but not necessarily in warm inflation, is provided. Next, the quantum field theory aspects in realizing explicit microscopic models for warm inflation are given. This includes the derivation of dissipation coefficients relevant in warm inflation for different particle field theory models. The dynamics of cosmological perturbations in warm inflation are then described. The general expression for the curvature scalar power spectrum is shown. We then discuss in details the relevant regimes of warm inflation, the weak and strong dissipative regimes. We also discuss the results predicted in these regimes of warm inflation and how they are confronted with the observational data. We explain how the dissipative dynamics in warm inflation can address several long-standing issues related to (post-) inflationary cosmology. This includes recent discussions concerning the so-called swampland criteria and how warm inflation can belong to the landscape of string theory.