6 papers
(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…
Scalar Cosmological Perturbations from Quantum Gravitational Entanglement
Alexander F. Jercher, Luca Marchetti, Andreas G. A. Pithis
A major challenge at the interface of quantum gravity and cosmology is to explain the emergence of the large-scale structure of the Universe from Planck scale physics. In this lett…
Scale invariance beyond criticality within the mean-field analysis of tensorial field theories
Roukaya Dekhil, Alexander F. Jercher, Daniele Oriti +1
We continue the series of articles on the application of Landau-Ginzburg mean-field theory to unveil the basic phase structure of tensorial field theories which are characterized b…
Phase transitions in TGFT: Landau-Ginzburg analysis of the causally complete Lorentzian Barrett-Crane model
Roukaya Dekhil, Alexander F. Jercher, Andreas G. A. Pithis
It is expected that continuum spacetime emerges via phase transition in the tensorial group field theory (TGFT) approach to quantum gravity. Recent work on the application of Landa…
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…
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…