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WS26/27 – Abstract
Sebastian Steinhaus
(Friedrich-Schiller-Universität Jena)
12.11.2026
Cosmological path integrals in effective spin foams
Spin foam models are a promising approach to quantum gravity, aiming for non-perturbatively evaluating gravitational path integrals. Effective spin foams, an ad-hoc model capturing essential features like discrete area spectra, are the most computable models.
In this talk, I will apply effective spin foams to cosmological path integrals. To this end, I first introduce (spatially flat) classical Regge cosmological models. I solve the classical dynamics numerically and explore the continuum limit. Then, I evaluate the Lorentzian, non-Wick-rotated path integral via a transfer matrix method and compute expectation values. In comparison to the classical solution, I identify a semi-classical regime, but also realize that the results are discretization dependent. To obtain consistent results, the coupling constants must be varied, which opens a perspective on renormalization in spin foams.
