Nikolaos Tetradis

In this way we obtain∂ η P ab (k, η) = −Ω ac P cb (k, η) − Ω bc P ac (k, η)+e η ∫d 3 q [ γ acd (k, −q, q − k)B bcd (k, −q, q − k)+γ bcd (k, −q, q − k)B acd (k, −q, q − k) ] ,∂ η B abc (k, −q, q − k) = −Ω ad B dbc (k, −q, q − k) − Ω bd B adc (k, −q, q − k)−Ω cd B abd (k, −q, q − k)+2e η ∫d 3 q [ γ ade (k, −q, q − k)P db (q, η)P ec (k − q, η)+γ bde (−q, q − k, k)P dc (k − q, η)P ea (k, η)+γ cde (q − k, k, −q)P da (k, η)P eb (q, η) ] .Similarity with the Exact Renormalization Group (Wilson 1971).Path integral representation.Vertex expansion of the effective action.J. Berges, N. T., C. Wetterich, Phys. Rep. 363: 223 (2002)N. Tetradis University of AthensThe inhomogeneity of the Universe and the cosmological model