3 papers
gr-qc2025
(2+1) Lorentzian quantum cosmology from spin-foams: opportunities and obstacles for semi-classicality
Alexander F. Jercher, José Diogo Simão, Sebastian Steinhaus
We construct an effective cosmological spin-foam model for a (2+1) dimensional spatially flat universe, discretized on a hypercubical lattice, containing both space- and time-like…
gr-qc2024
Partial absence of cosine problem in 3d Lorentzian spin foams
Alexander F. Jercher, José Diogo Simão, Sebastian Steinhaus
We study the semi-classical limit of the recently proposed coherent spin foam model for (2+1) Lorentzian quantum gravity. Specifically, we analyze the gluing equations derived from…
gr-qc2024
Cosmology in Lorentzian Regge calculus: causality violations, massless scalar field and discrete dynamics
Alexander F. Jercher, Sebastian Steinhaus
We develop a model of spatially flat, homogeneous and isotropic cosmology in Lorentzian Regge calculus, employing 4-dimensional Lorentzian frusta as building blocks. By examining t…