Title: Complex critical point and effective dynamics of spinfoam quantum gravity

Speaker: Dr. Dongxue Qu (Perimeter Institute, Canada)

Spacetime Point:
A311 Science and Technology Building
Online (202.112.92.14)
2:30pm-4:00pm, June 7th (Wed.)

Abstract: This talk will base 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-$\Delta_3$ simplicial complex.