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Lorentzian spin foam amplitudes: graphical calculus and asymptotics

- J. Barrett, R. J. Dowdall, W. Fairbairn, F. Hellmann, R. Pereira
- Mathematics
- 14 July 2009

The amplitude for the 4-simplex in a spin foam model for quantum gravity is defined using a graphical calculus for the unitary representations of the Lorentz group. The asymptotics of this amplitude… Expand

Loop-quantum-gravity vertex amplitude.

- J. Engle, R. Pereira, C. Rovelli
- PhysicsPhysical review letters
- 16 May 2007

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Regularization and finiteness of the Lorentzian loop quantum gravity vertices

- J. Engle, R. Pereira
- Mathematics
- 30 May 2008

We give an explicit form for the Lorentzian vertices recently introduced for possibly defining the dynamics of loop quantum gravity. As a result of doing so, a natural regularization of the vertices… Expand

Asymptotics of 4d spin foam models

- J. Barrett, R. J. Dowdall, W. Fairbairn, H. Gomes, F. Hellmann, R. Pereira
- Mathematics
- 9 March 2010

We study the asymptotic properties of four-simplex amplitudes for various four-dimensional spin foam models. We investigate the semi-classical limit of the Ooguri, Euclidean and Lorentzian EPRL… Expand

Wheeler-DeWitt quantization can solve the singularity problem

- F. Falciano, R. Pereira, N. Pinto-Neto, E. S. Santini
- Physics
- 18 June 2012

We study the Wheeler-DeWitt quantum cosmology of a spatially flat Friedmann cosmological model with a massless free scalar field. We compare the consistent histories approach with the de Broglie-Bohm… Expand

Coherent states in quantum gravity: a construction based on the flux representation of loop quantum gravity

- D. Oriti, R. Pereira, L. Sindoni
- Physics
- 26 October 2011

As part of a wider study of coherent states in (loop) quantum gravity, we introduce a modification to the standard construction, based on the recently introduced (non-commutative) flux… Expand

Coherent states, constraint classes and area operators in the new spin-foam models

- J. Engle, R. Pereira
- Physics
- 26 October 2007

Recently, two new spin-foam models have appeared in the literature, both motivated by a desire to modify the Barrett–Crane model in such a way that the imposition of certain second class constraints,… Expand

Lorentzian loop quantum gravity vertex amplitude

- R. Pereira
- Physics
- 1 April 2008

We generalize a model recently proposed for Euclidean quantum gravity to the case of Lorentzian signature. The main features of the Euclidean model are preserved in the Lorentzian one. In particular,… Expand

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