59 citations · 202 across the 9 of their papers we have counts for
9 papers
Emergent 4-dimensional linearized gravity from spin foam model
Muxin Han, Zichang Huang, Antonia Zipfel
Spin Foam Models (SFMs) are covariant formulations of Loop Quantum Gravity (LQG) in 4 dimensions. This work studies the perturbations of SFMs on a flat background. It demonstrates…
Spin foam propagator: A new perspective to include a cosmological constant
Muxin Han, Zichang Huang, Antonia Zipfel
In recent years, the calculation of the first non-vanishing order of the metric 2-point function or graviton propagator in a semiclassical limit has evolved as a standard test for…
On the relation between reduced quantisation and quantum reduction for spherical symmetry in loop quantum gravity
Norbert Bodendorfer, Antonia Zipfel
Building on a recent proposal for a quantum reduction to spherical symmetry from full loop quantum gravity, we investigate the relation between a quantisation of spherically symmet…
Stable coherent states
Antonia Zipfel, Thomas Thiemann
We analyze the stability under time evolution of complexifier coherent states (CCS) in one-dimensional mechanical systems. A system of coherent states is called stable if it evolve…
The Lorentzian proper vertex amplitude: Asymptotics
Jonathan Engle, Ilya Vilensky, Antonia Zipfel
In previous work, the Lorentzian proper vertex amplitude for a spin-foam model of quantum gravity was derived. In the present work, the asymptotics of this amplitude are studied in…
The Lorentzian proper vertex amplitude: Classical analysis and quantum derivation
Jonathan Engle, Antonia Zipfel
Spin foam models, an approach to defining the dynamics of loop quantum gravity, make use of the Plebanski formulation of gravity, in which gravity is recovered from a topological f…
Matrix Elements of Lorentzian Hamiltonian Constraint in LQG
Emanuele Alesci, Klaus Liegener, Antonia Zipfel
The Hamiltonian constraint is the key element of the canonical formulation of LQG coding its dynamics. In Ashtekar-Barbero variables it naturally splits into the so called Euclidea…
Linking covariant and canonical LQG II: Spin foam projector
Thomas Thiemann, Antonia Zipfel
In a seminal paper, Kaminski, Kisielowski an Lewandowski for the first time extended the definition of spin foam models to arbitrary boundary graphs. This is a prerequisite in orde…
Linking covariant and canonical LQG: new solutions to the Euclidean Scalar Constraint
Emanuele Alesci, Thomas Thiemann, Antonia Zipfel
It is often emphasized that spin-foam models could realize a projection on the physical Hilbert space of canonical Loop Quantum Gravity (LQG). As a first test we analyze the one-ve…