Warm Inflationary Dynamics in Cosmological Models
Summary
Warm inflation represents a paradigm in early‐Universe cosmology in which the accelerated expansion driven by a scalar inflaton field occurs in the presence of a thermal radiation bath. Dissipative interactions between the inflaton and other fields source a non‐negligible radiation component throughout the inflationary epoch, thereby modifying the classical slow‐roll conditions and the generation of primordial perturbations. Unlike the traditional cold inflation scenario, warm inflation naturally incorporates reheating and can alleviate issues of initial‐condition fine‐tuning. The continuous energy transfer from the inflaton to the radiation bath introduces a friction term in the field equation, which can sustain slow‐roll dynamics even on steeper potentials. The resulting perturbation spectra acquire both quantum and thermal contributions, leading to distinct predictions for the scalar spectral index and tensor‐to‐scalar ratio. Moreover, warm inflationary frameworks provide fertile ground for embedding high-energy physics considerations, including consistency with conjectures arising in quantum gravity and potential mechanisms for the production of dark matter during the inflationary phase.
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Warm Inflationary Dynamics in Cosmological Models publication trend
The graph below shows the total number of articles in warm inflationary dynamics in cosmological models across all publications each year (not limited to Nature Index journals).
Technical terms
Warm inflation: An inflationary scenario in which the inflaton’s decay into lighter particles maintains a thermal radiation bath throughout the accelerated expansion.
Inflaton field: A hypothetical scalar field whose potential energy drives the rapid expansion of the early Universe.
Dissipation coefficient: A parameter quantifying the rate at which the inflaton transfers energy to the radiation bath, acting as a friction term in the field equation.
Scalar spectral index: A dimensionless quantity that characterises the scale dependence of primordial density fluctuations.
Tensor-to-scalar ratio: The ratio of the amplitudes of primordial gravitational waves to density perturbations, used to distinguish between inflationary models.
Swampland conjectures: Criteria proposed in quantum gravity suggesting which low-energy effective theories can arise from a consistent ultraviolet completion.
References
- Perturbation Spectra of Warm Inflation in f(Q, T) Gravity. The Astrophysical Journal (2024).
- Dark Matter freeze-in during warm inflation and the seesaw mechanism. Journal of High Energy Physics (2025).
- Warm β-exponential inflation and the swampland conjectures. European Physical Journal C (2023).
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