Group Field Theory: Coarse-Graining and Effective Cosmology

by Andreas Pithis (Jena University)

Thursday 10 Jul 2025, 14:15 → 15:45 Europe/Berlin

Abbeanum/1-HS2 - Straubel-HS (TPI, FSU Jena)

Group Field Theory (GFT) models for Lotentzian quantum gravity are state-sum models which provide tentative quantizations of first order Lorentzian Palatini and Palatini-Holst gravity written as a constrained BF-theory. In this overview talk a general introduction to the GFT framework (with relations to spin foam and tensor models) is given. Then the talk focusses on what is known about coarse-graining in GFT (renormalisation and mean-field theory) to extract information about the phase structure of interesting models. Finally, we discuss how the mean-field dynamics of a condensate phase can be mapped to effective continuum cosmological dynamics which successfully reproduce the Friedmann dynamics for spatially homogeneous and isotropic flat geometries. This work is based among others on arXiv:1904.00598, arXiv:2112.00091, arXiv:2206.15442, arXiv:2209.04297 and arXiv:2211.12768, arXiv:2305.06136, arXiv:2404.04524 andarXiv:2407.02325 and arXiv:2411.12628.