Particle creation and warm inflation

Abstract

During cosmological inflation, it has been suggested that fields coupled to the inflaton can be excited by the slow-rolling inflaton into a quasi-stable non-vacuum state. Within this scenario of ``warm inflation'', this could allow for a smooth transition to a radiation dominated Universe without a separate reheating stage and a modification of the slow roll evolution, as the heat-bath backreacts on the inflaton through friction. In order to study this from first principles, we investigate the dynamics of a scalar field coupled to the inflaton and N light scalar boson fields, using the 2PI-1/N expansion for nonequilibrium quantum fields. As a first step we restrict ourselves to Minkowski spacetime, interpret the inflaton as a time-dependent background, and use vacuum initial conditions. We find that the dominant effect is particle creation at late stages of the evolution due to the effective time-dependent mass. The further transfer of energy to the light degrees of freedom and subsequent equilibration only occurs after the end of inflation. As a consequence, the adiabatic constraint, which is assumed in most studies of warm inflation, is not satisfied when starting from an initial vacuum state.

14 pages, 4 eps figures; minor changes, refs added, to appear in PLB

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Cited by in corpus (11)

• Kadanoff-Baym Equations with Non-Gaussian Initial Conditions: The Equilibrium Limit
• Quantum field thermalization in expanding backgrounds
• Particle production and reheating in the inflationary universe
• Local Approximations for Effective Scalar Field Equations of Motion
• Warm inflation dynamics in the low temperature regime
• 2PI functional techniques for gauge theories: QED
• On the Langevin description of nonequilibrium quantum fields
• Thermal effects on slow-roll dynamics
• Effective convergence of the 2PI-1/N expansion for nonequilibrium quantum fields
• Fast Electroweak Symmetry Breaking and Cold Electroweak Baryogenesis
• Particle production and hadronization temperature in the massive Schwinger model