| Abstract: |
Gravitational particle production inevitably occurs after the end of inflation, and thus any particle, including dark matter, could in principle be created by this process. To study this production channel, two different approaches have commonly been considered, one of which is based on the Boltzmann equation, and the other is based on the Bogoliubov transformation. The former approach has widely been used in phenomenological studies of dark matter, while the latter has been developed to describe particle production in curved spacetime. I will discuss when these two approaches are equivalent and when they are not by considering the pure gravitational production of scalar particle. |
