# Particle production in a Robertson-Walker space with a de Sitter phase of finite extension

## TL;DR

This paper analyzes particle production in a universe with a finite de Sitter phase, showing that particle densities reach a steady state and can exhibit thermal spectra depending on the field type and parameters.

## Contribution

It provides a detailed calculation of particle production in a finite de Sitter phase, highlighting differences between scalar and spinorial fields and conditions for thermal spectra.

## Key findings

- Particle density approaches a constant at the Hubble time scale
- Spinorial field spectrum can be exactly thermal
- Scalar field spectrum is nearly thermal under certain parameters

## Abstract

We investigate the phenomenon of particle production in a Friedmann-Robertson-Walker universe which contains a phase of de Sitter expansion for a finite interval, outside which it reduces to the flat Minkowski spacetime. We compute the particle number density for a massive scalar and a spinorial field and point out differences between the two cases. We find that the resulting particle density approaches a constant value at the scale of the Hubble time and that for a certain choice of the parameters the spectrum is precisely thermal for the spinorial field, and almost thermal for the scalar field.