Effective action for EPRL/FK spin foam models

TL;DR

This paper introduces a modified EPRL/FK spin foam model that remains finite and reproduces Einstein-Hilbert action at large spins, providing a framework for calculating quantum corrections in quantum gravity.

Contribution

It proposes a natural modification to the EPRL/FK vertex amplitude resulting in a finite spin foam model with correct classical limit and computable quantum corrections.

Findings

The modified model is finite and well-defined.

The effective action reproduces Einstein-Hilbert action at large spins.

Quantum corrections can be systematically calculated.

Abstract

We show that a natural modification of the EPRL/FK vertex amplitude gives a finite spin foam model whose effective action gives the Einstein-Hilbert action in the limit of large spins and arbitrarily fine spacetime triangulations. The first-order quantum corrections can be easily computed and we show how to calculate the higher-order corrections.