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Collisional equilibrium, particle production and the inflationary universe

Winfried Zimdahl·Josep Triginer·Diego Pavon
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Abstract

Particle production processes in the expanding universe are described within a simple kinetic model. The equilibrium conditions for a Maxwell-Boltzmann gas with variable particle number are investigated. We find that radiation and nonrelativistic matter may be in equilibrium at the same temperature provided the matter particles are created at a rate that is half the expansion rate. Using the fact that the creation of particles is dynamically equivalent to a nonvanishing bulk pressure we calculate the backreaction of this process on the cosmological dynamics. It turns out that the `adiabatic' creation of massive particles with an equilibrium distribution for the latter necessarily implies power-law inflation. Exponential inflation in this context is shown to become inconsistent with the second law of thermodynamics after a time interval of the order of the Hubble time.

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Winfried Zimdahl, Josep Triginer, Diego Pavon. 1996-08-16. Collisional equilibrium, particle production and the inflationary universe. https://doi.org/10.1103/physrevd.54.6101

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