Effective spin foam models for Lorentzian quantum gravity

@article{Asante2021EffectiveSF,
  title={Effective spin foam models for Lorentzian quantum gravity},
  author={Seth K. Asante and Bianca Dittrich and Jos{\'e} Padua-Arg{\"u}elles},
  journal={Classical and Quantum Gravity},
  year={2021},
  volume={38}
}
Making the Lorentzian path integral for quantum gravity well-defined and computable has been a long standing challenge. In this work we adopt the recently proposed effective spin foam models to the Lorentzian case. This defines a path integral over discrete Lorentzian quantum geometric configurations, which include metric and torsion degrees of freedom. The torsion degrees of freedom arise due to an anomaly, which is parameterized by the Barbero–Immirzi parameter. Requiring a semi-classical… 

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