University thesis:
Dissertation, Georg-August-Universität Göttingen, 2018
Footnote:
Description:
In a quantum field theory with a time-dependent background, as in an expanding universe, the time-translational symmetry is broken. We therefore expect loop corrections to cosmological observables to be time-dependent after renormalization for interacting fields. In this thesis we compute and discuss such radiative corrections to the primordial spectrum and higher order spectra in simple inflationary models. We investigate both massless and massive virtual fields, and we disentangle the time dependence caused by the background and by the initial state that is set to the Bunch-Davies vacuum ...