Complex critical point and effective dynamics of spinfoam quantum gravity (Dongxue Qu, Perimeter Institute) FAU^2 Talk

This talk will be based on the paper arXiv:2301.02930. I will introduce the complex critical points in the 4-dimensional Lorentzian Engle-Pereira-Rovelli-Livine (EPRL) spinfoam model in the large-𝑗 regime. For the 4-simplex amplitude, taking into account the complex critical point generalizes the large-𝑗 asymptotics to the situation with non-Regge boundary data and relates to the twisted geometry. For generic simplicial complexes, I will present a general procedure to derive the effective theory of Regge geometries from the spinfoam amplitude in the large-𝑗 regime by using the complex critical points. The effective theory is analyzed in detail for the spinfoam amplitude on the double-Δ3 simplicial complex.