Speaker
Spyros Sypsas
Description
The partition function of a scalar field theory can be computed order by order in the interaction potential within perturbative quantum field theory. We will show that when there exists a separation of scales, the statistics of the long/slow field-modes obey a Fokker-Planck equation exhibiting nonstandard probability drift and diffusion due to short/fast dynamics. Our main application will be scalar physics on de Sitter space (where the Hubble radius provides the required scale separation) but the results extend to any open system with this property.