Decay of the de Sitter Vacuum

Understand

The decay rate of the Bunch-Davies state of a massive scalar field in the expanding flat spatial sections of de Sitter space is determined by an analysis of the particle pair creation process in real time.

• The Feynman definition of particle and antiparticle Fourier mode solutions of the scalar wave equation, and their adiabatic phase analytically continued to the complexified time domain, show conclusively that the Bunch-Davies state is not the vacuum state at late times.
• The closely analogous creation of charged particle pairs in a uniform electric field is reviewed and Schwinger's result for the vacuum decay rate is recovered by the real time analysis.
• The vacuum decay rate in each case is also calculated by switching the background field on adiabatically, allowing it to act for a very long time, and then adiabatically switching it off again.