Cosine problem in EPRL/FK spinfoam model

Abstract

We calculate the classical limit effective action of the EPRL/FK spinfoam model of quantum gravity coupled to matter fields. By employing the standard QFT background field method adapted to the spinfoam setting, we find that the model has many different classical effective actions. Most notably, these include the ordinary Einstein-Hilbert action coupled to matter, but also an action which describes antigravity. All those multiple classical limits appear as a consequence of of the fact that the EPRL/FK vertex amplitude has cosine-like large spin asymptotics. We discuss some possible ways to eliminate the unwanted classical limits.

v3: Published version. 23 pages

References in corpus (6)

• LQG vertex with finite Immirzi parameter
• A new spinfoam vertex for quantum gravity
• Zakopane lectures on loop gravity
• Face amplitude of spinfoam quantum gravity
• Discrete Symmetries in Covariant LQG
• Semiclassical regime of Regge calculus and spin foams

Cited by in corpus (5)

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• Causal structure in spin-foams
• A note on the spinor construction of Spin Foam amplitudes
• Symmetry breaking mechanisms of the 3BF action for the Standard Model coupled to gravity
• Loop quantum gravity with optimal control path integral, and application to black hole tunneling