Journal of High Energy Physics

, 2018:63 | Cite as

Adiabatic out-of-equilibrium solutions to the Boltzmann equation in warm inflation

  • Mar Bastero-Gil
  • Arjun Berera
  • Rudnei O. Ramos
  • João G. RosaEmail author
Open Access
Regular Article - Theoretical Physics


We show that, in warm inflation, the nearly constant Hubble rate and temperature lead to an adiabatic evolution of the number density of particles interacting with the thermal bath, even if thermal equilibrium cannot be maintained. In this case, the number density is suppressed compared to the equilibrium value but the associated phase-space distribution retains approximately an equilibrium form, with a smaller amplitude and a slightly smaller effective temperature. As an application, we explicitly construct a baryogenesis mechanism during warm inflation based on the out-of-equilibrium decay of particles in such an adiabatically evolving state. We show that this generically leads to small baryon isocurvature perturbations, within the bounds set by the Planck satellite. These are correlated with the main adiabatic curvature perturbations but exhibit a distinct spectral index, which may constitute a smoking gun for baryogenesis during warm inflation. Finally, we discuss the prospects for other applications of adiabatically evolving out-of-equilibrium states.


Cosmology of Theories beyond the SM Thermal Field Theory 


Open Access

This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.


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Copyright information

© The Author(s) 2018

Authors and Affiliations

  • Mar Bastero-Gil
    • 1
  • Arjun Berera
    • 2
  • Rudnei O. Ramos
    • 3
  • João G. Rosa
    • 4
    Email author
  1. 1.Departamento de Física Teórica y del CosmosUniversidad de GranadaGranadaSpain
  2. 2.School of Physics and AstronomyUniversity of EdinburghEdinburghUnited Kingdom
  3. 3.Departamento de Física TeóricaUniversidade do Estado do Rio de JaneiroRio de JaneiroBrazil
  4. 4.Departamento de Física da Universidade de Aveiro and CIDMAAveiroPortugal

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