The warm inflation story

Abstract

Warm inflation has normalized two ideas in cosmology, that in the early universe the initial primordial density perturbations generally could be of classical rather than quantum origin and that during inflation, particle production from interactions amongst quantum field, and its backreaction effects, can occur concurrent with inflationary expansion. When we first introduced these ideas, both were met with resistance, but today they are widely accepted as possibilities with many models and applications based on them, which is an indication of the widespread influence of warm inflation. Open quantum field theory, which has been utilized in studies of warm inflation, is by now a relevant subject in cosmology, in part due to this early work. In this review I first discuss the basic warm inflation dynamics. I then outline how to compute warm inflation dynamics from first principles quantum field theory (QFT) and in particular how a dissipative term arises. Warm inflation models can have an inflaton mass bigger than the Hubble scale and the inflaton field excursion can remain sub-Planckian, thus overcoming the most prohibitive problems of inflation model building. I discuss the early period of my work in developing warm inflation that helped me arrive at these important features of its dynamics. Inflationary cosmology today is immersed in hypothetical models, which by now are acting as a diversion from reaching any endgame in this field. I discuss better ways to approach model selection and give necessary requirements for a well constrained and predictive inflation model. A few warm inflation models are pointed out that could be developed to this extent. I discuss how at this stage more progress would be made in this subject by taking a broader view on the possible early universe solutions that include not just inflation but the diverse range of options.

32 pages, published in Universe 2023

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Cited by in corpus (33)

• The Open Effective Field Theory of Inflation
• Improved Predictions on Higgs-Starobinsky Inflation and Reheating with ACT DR6 and Primordial Gravitational Waves
• Energy-Momentum Squared Gravity: A Brief Overview
• Quantum thermodynamics of de Sitter space
• A generalized method of constraining Warm Inflation with CMB data
• Stability analysis of warm quintessential dark energy model
• WI2easy: warm inflation dynamics made easy
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• Evolution of coupled scalar perturbations through smooth reheating. I. Dissipative regime
• Perturbation Spectra of Warm Inflation in $f(Q,T)$ Gravity
• Embedding Ultra slow-roll inflaton dynamics in Warm Inflation
• Warming up the Fibres
• A comparative analysis of dissipation coefficients in warm inflation
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• Coupled quintessence inspired by warm inflation
• Dark Matter Freeze-In during Warm Inflation and the Seesaw Mechanism
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• Thermodynamics of the Primordial Universe
• Reassessing constant-roll Warm Inflation
• Purely gravitational dark matter production in warm inflation
• No Warm Inflation From a Vanilla Axion
• Evolution of coupled scalar perturbations through smooth reheating. II. Thermal fluctuation regime
• Defying eternal inflation in warm inflation with a negative running
• Unraveling the Hubble tension with warm inflation
• Stage IV CMB forecasts for warm inflation
• Witten-O'Raifeartaigh potential revisited in the context of Warm Inflation
• Violation of Bell inequalities from Cosmic Microwave Background data
• Gravitational waves from warm inflation in the weak dissipative regime
• Warm inflation in Weyl geometric gravity
• Warm Inflation Beyond the Markovian Limit
• Phantom cosmology with arbitrary potential: New accelerating scaling attractors
• Constraints on polynomial inflation under power-law perturbations