Renormalisation group flow for scalar fields in De Sitter space

by Maxime Guilleux (APC Paris 7)

Wednesday 17 Jun 2015, 16:00 → 17:00 Europe/Berlin

3344 (TUM Physik Department)

Quantum field theory on curved space-time is most relevant to several open questions in cosmology. In relation with inflation, we study O(N) scalar field theories in de Sitter space. For light fields in units of the space-time curvature these feature non-trivial quantum effects on superhorizon scales that require resummation techniques. Using non-perturbative renormalization group methods, we derive a flow equation for the (quantum) effective action which allows us to study the flow of the effective potential from sub- to superhorizon scales. This efficiently captures several nontrivial effects induced by the curvature, such as effective dimensional reduction, symmetry restoration, or mass generation. Finally, we show that our approach provides an alternative derivation of the stochastic description of Starobinsky and Yokoyama and provides a unified description of the latter and of Euclidean de Sitter space.