A discretization of Holst's action for general relativity

Abstract

We present a simplicial model for gravity written in terms of a discretized Lorentz connection and a discretized tetrad field. The continuum limit of its action is Holst's action for general relativity. With the intention of using it to construct spin foam modes for quantum gravity, we write two other equivalent models written in terms of a discretized and constrained $B$ field. The differences between our model and existing models are most likely inessential in the sense that a quantization would lead to equivalent quantum theories in the Wilsonian continuum limit. Nevertheless, we mention two features leading to possible advantages: Curvature degrees of freedom are described at the level of each 4-simplex. Our model offers a picture of bulk geometry leading to actions for matter couplings that split as a sum over 4-simplices.

25 pagas, 1 figure

References in corpus (11)

• LQG vertex with finite Immirzi parameter
• A New Spin Foam Model for 4d Gravity
• Extended corner symmetry, charge bracket and Einstein's equations
• Area-angle variables for general relativity
• Effective Spin Foam Models for Lorentzian Quantum Gravity
• A spin foam model for general Lorentzian 4-geometries
• Boundary and Corner Terms in the Action for General Relativity
• Spinfoam on Lefschetz Thimble: Markov Chain Monte-Carlo Computation of Lorentzian Spinfoam Propagator
• Discrete gravity dynamics from effective spin foams
• Finiteness of spinfoam vertex amplitude with timelike polyhedra, and the full amplitude
• Homotopy data as part of the lattice field: A first study