Timelike surfaces in Lorentz covariant loop gravity and spin foam models

Sergei Alexandrov (1) , Zoltan Kadar

1 LPTENS - Laboratoire de Physique Théorique de l'ENS [École Normale Supérieure]

We construct a canonical formulation of general relativity for the case of a timelike foliation of spacetime. The formulation possesses explicit covariance with respect to Lorentz transformations in the tangent space. Applying the loop approach to quantize the theory we derive the spectrum of the area operator of a two-dimensional surface. Its different branches are naturally associated to spacelike and timelike surfaces. The results are compared with the predictions of Lorentzian spin foam models. A restriction of the representations labeling spin networks leads to perfect agreement between the states as well as the area spectra in the two approaches.

Domaines: Relativité Générale et Cosmologie Quantique [gr-qc]

Sergei Alexandrov, Zoltan Kadar. Timelike surfaces in Lorentz covariant loop gravity and spin foam models. Classical and Quantum Gravity, 2005, 22, pp.3491-3510. ⟨hal-00009307⟩