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 EinsteinHilbert action coupled to matter, but also an action which describes antigravity. All those multiple classical limits appear as a consequence of the fact that the EPRL/FK vertex amplitude has cosinelike large spin asymptotics. We discuss some possible ways to eliminate the unwanted classical limits.
 Publication:

General Relativity and Gravitation
 Pub Date:
 January 2014
 DOI:
 10.1007/s1071401316168
 arXiv:
 arXiv:1307.5352
 Bibcode:
 2014GReGr..46.1616V
 Keywords:

 Loop quantum gravity;
 Spin foam models;
 Classical limit;
 EPRL/FK model;
 General Relativity and Quantum Cosmology;
 High Energy Physics  Theory;
 Mathematical Physics
 EPrint:
 v3: Published version. 23 pages