Effective Spin Foam Models for Lorentzian Quantum Gravity
arXiv:2104.00485 · doi:10.1088/1361-6382/ac1b44
Abstract
Making the Lorentzian path integral for quantum gravity well-defined and computable has been a long standing challenge. In this work we adopt the recently proposed effective spin foam models to the Lorentzian case. This defines a path integral over discrete Lorentzian quantum geometric configurations, which include metric and torsion degrees of freedom. The torsion degrees of freedom arise due to an anomaly, which is parametrized by the Barbero--Immirzi parameter. Requiring a semi-classical regime constrains this parameter, but the precise bound has to be determined by probing the dynamics. The effective models provide the computationally most efficient spin foam models yet, which allows us to perform first tests for determining the semi-classical regime. This includes explorations specific to the Lorentzian case, e.g. investigating quantum geometries with null lengths and null areas as well as geometries that describe a change of spatial topology.
arXiv comment34 pages, 15 figures (Accepted to Classical and Quantum Gravity Journal)
References in corpus (99)
- Background Independent Quantum Gravity: A Status Report
- Discreteness of area and volume in quantum gravity
- Quantum Theory of Gravity I: Area Operators
- Real Ashtekar Variables for Lorentzian Signature Space-times
- The Spin Foam Approach to Quantum Gravity
- LQG vertex with finite Immirzi parameter
- Introduction to Modern Canonical Quantum General Relativity
- Emergence of a 4D World from Causal Quantum Gravity
- Real and complex connections for canonical gravity
- A new spinfoam vertex for quantum gravity
- Non-perturbative Lorentzian Quantum Gravity, Causality and Topology Change
- A New Spin Foam Model for 4d Gravity
- High density QCD on a Lefschetz thimble?
- The loop-quantum-gravity vertex-amplitude
- Dynamically Triangulating Lorentzian Quantum Gravity
- Lorentzian spin foam amplitudes: graphical calculus and asymptotics
- Polyhedra in loop quantum gravity
- Asymptotic analysis of the EPRL four-simplex amplitude
- Lorentzian Quantum Cosmology
- On the semiclassical limit of 4d spin foam models
- A non-perturbative Lorentzian path integral for gravity
- The Nonperturbative Quantum de Sitter Universe
- Introduction to Loop Quantum Cosmology
- Phase space descriptions for simplicial 4d geometries
- Improved and Perfect Actions in Discrete Gravity
- Consistently Solving the Simplicity Constraints for Spinfoam Quantum Gravity
- A second-order phase transition in CDT
- Area-angle variables for general relativity
- Quantum tetrahedra and simplicial spin networks
- Coarse graining methods for spin net and spin foam models
- Quantum deformation of quantum gravity
- Complex actions in two-dimensional topology change
- Decorated tensor network renormalization for lattice gauge theories and spin foam models
- Numerical evidence for a phase transition in 4d spin foam quantum gravity
- Spin foam models for quantum gravity from lattice path integrals
- Quantum geometry from phase space reduction
- Perfect discretization of reparametrization invariant path integrals
- Regge calculus from a new angle
- SL(2,C) Chern-Simons Theory, a non-Planar Graph Operator, and 4D Loop Quantum Gravity with a Cosmological Constant: Semiclassical Geometry
- Simplicity in simplicial phase space
- A note on area variables in Regge calculus
- Effective Spin Foam Models for Four-Dimensional Quantum Gravity
- Linearized dynamics from the 4-simplex Regge action
- From covariant to canonical formulations of discrete gravity
- Numerical study of the Lorentzian Engle-Pereira-Rovelli-Livine spin foam amplitude
- Semi-Classical Limits of Simplicial Quantum Gravity
- Towards a phase diagram for spin foams
- Path integral measure and triangulation independence in discrete gravity
- Canonical simplicial gravity
- Time evolution as refining, coarse graining and entangling
- Breaking and restoring of diffeomorphism symmetry in discrete gravity
- Holonomy spin foam models: Asymptotic geometry of the partition function
- Asymptotics of Spinfoam Amplitude on Simplicial Manifold: Euclidean Theory
- Coarse graining flow of spin foam intertwiners
- A spin foam model for general Lorentzian 4-geometries
- Numerical methods for EPRL spin foam transition amplitudes and Lorentzian recoupling theory
- Causal Dynamical Triangulations without Preferred Foliation
- First order Regge calculus
- Fock representation of gravitational boundary modes and the discreteness of the area spectrum
- Observables in Loop Quantum Gravity with a cosmological constant
- The End of a Black Hole's Evaporation -- Part I
- Boosting Wigner's nj-symbols
- Quasi-local holographic dualities in non-perturbative 3d quantum gravity I - Convergence of multiple approaches and examples of Ponzano-Regge statistical duals
- Quantum group spin nets: refinement limit and relation to spin foams
- A high-performance code for EPRL spin foam amplitudes
- A proposed proper EPRL vertex amplitude
- Quantum gravity kinematics from extended TQFTs
- Renormalization of symmetry restricted spin foam models with curvature in the asymptotic regime
- Spinfoam on Lefschetz Thimble: Markov Chain Monte-Carlo Computation of Lorentzian Spinfoam Propagator
- Semiclassical Analysis of Spinfoam Model with a Small Barbero-Immirzi Parameter
- On Spinfoam Models in Large Spin Regime
- A spin-foam vertex amplitude with the correct semiclassical limit
- Discretization independence implies non-locality in 4D discrete quantum gravity
- Poincare 2-group and quantum gravity
- Regge gravity from spinfoams
- Quasi-local holographic dualities in non-perturbative 3d quantum gravity
- Numerical analysis of spin foam dynamics and the flatness problem
- Asymptotic analysis of the EPRL model with timelike tetrahedra
- Quasi-local holographic dualities in non-perturbative 3d quantum gravity II - From coherent quantum boundaries to BMS3 characters
- On the role of the Barbero-Immirzi parameter in discrete quantum gravity
- A Discrete and Coherent Basis of Intertwiners
- Spin foams with timelike surfaces
- The spin connection of twisted geometry
- Towards a Cosmological subsector of Spin Foam Quantum Gravity
- Emergence of gravity from spinfoams
- Spikes in Quantum Regge Calculus
- Constraints on Area Variables in Regge Calculus
- Addendum: EPRL/FK Asymptotics and the Flatness Problem
- A complex path around the sign problem
- Generating Functions for Coherent Intertwiners
- Searching for classical geometries in spin foam amplitudes: a numerical method
- (3+1)-dimensional topological phases and self-dual quantum geometries encoded on Heegard surfaces
- EPRL/FK Asymptotics and the Flatness Problem
- Fixed-Topology Lorentzian Triangulations: Quantum Regge Calculus in the Lorentzian Domain
- Non-Perturbative 3D Quantum Gravity: Quantum Boundary States and Exact Partition Function
- Realizability of the Lorentzian (n,1)-Simplex
- Loop Quantum Gravity's Boundary Maps
- Causal Dynamical Triangulations in the Spincube Model of Quantum Gravity
- Lorentzian angles and trigonometry including lightlike vectors
Cited by in corpus (27)
- Complex critical points and curved geometries in four-dimensional Lorentzian spinfoam quantum gravity
- A high-performance code for EPRL spin foam amplitudes
- Discrete gravity dynamics from effective spin foams
- How-To compute EPRL spin foam amplitudes
- From spin foams to area metric dynamics to gravitons
- Lorentzian quantum cosmology goes simplicial
- Torsion in string-inspired cosmologies and the universe dark sector
- Towards effective actions for the continuum limit of spin foams
- The Complete Barrett-Crane Model and its Causal Structure
- Mean-field phase transitions in TGFT quantum gravity
- Complex, Lorentzian, and Euclidean simplicial quantum gravity: numerical methods and physical prospects
- Asymptotic analysis of spin-foams with time-like faces in a new parameterisation
- Complex critical points in Lorentzian spinfoam quantum gravity: 4-simplex amplitude and effective dynamics on double- complex
- Spin-foams as semi-classical vertices: gluing constraints and a hybrid algorithm
- Markov Chain Monte Carlo methods for graph refinement in Spinfoam Cosmology
- Spinfoams and high performance computing
- Constraining the Barbero-Immirzi parameter from the duration of inflation in loop quantum cosmology
- Configuration space for quantum gravity in a locally regularized path integral
- Reconstructing the graviton
- Time-space duality in 2D quantum gravity
- Experimental Simulation of Loop Quantum Gravity on a Photonic Chip
- Toward matter dynamics in spin foam quantum gravity
- Modified Graviton Dynamics From Spin Foams: The Area Regge Action
- Geometry from local flatness in Lorentzian spin foam theories
- Light ray fluctuations in simplicial quantum gravity
- Light ray fluctuation and lattice refinement of simplicial quantum gravity
- A discretization of Holst's action for general relativity