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A Lagrangian approach to the Barrett-Crane spin foam model
Valentin Bonzom, Etera R. Livine
We provide the Barrett-Crane spin foam model for quantum gravity with a discrete action principle, consisting in the usual BF term with discretized simplicity constraints which in…
Matrix Models as Non-commutative Field Theories on R^3
Etera R. Livine
In the context of spin foam models for quantum gravity, group field theories are a useful tool allowing on the one hand a non-perturbative formulation of the partition function and…
A Note on B-observables in Ponzano-Regge 3d Quantum Gravity
Etera R. Livine, James P. Ryan
We study the insertion and value of metric observables in the (discrete) path integral formulation of the Ponzano-Regge spinfoam model for 3d quantum gravity. In particular, we dis…
The entropic boundary law in BF theory
Etera R. Livine, Daniel R. Terno
We compute the entropy of a closed bounded region of space for pure 3d Riemannian gravity formulated as a topological BF theory for the gauge group SU(2) and show its holographic b…
Towards the graviton from spinfoams: the complete perturbative expansion of the 3d toy model
Valentin Bonzom, Etera R. Livine, Matteo Smerlak +1
We consider an exact expression for the 6j-symbol for the isosceles tetrahedron, involving integrals over SU(2), and use it to write the two-point function of 3d gravity on a singl…
A Immirzi-like parameter for 3d quantum gravity
Valentin Bonzom, Etera R. Livine
We study an Immirzi-like ambiguity in three-dimensional quantum gravity. It shares some features with the Immirzi parameter of four-dimensional loop quantum gravity: it does not af…