We discuss various kinds of geometric bremsstrahlung processes in the spatially flat Robertson-Walker universe. Despite the fact that the temperature of the universe is much higher than particle masses and the Hubble parameter, the transition probability of these processes does not vanish. It is also pointed out that explicit forms of the probability possess a new duality with respect to the scale factor of the background geometry.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)