Observables in 3d spinfoam quantum gravity with fermions

Abstract

We study expectation values of observables in three-dimensional spinfoam quantum gravity coupled to Dirac fermions. We revisit the model introduced by one of the authors and extend it to the case of massless fermionic fields. We introduce observables, analyse their symmetries and the corresponding proper gauge fixing. The Berezin integral over the fermionic fields is performed and the fermionic observables are expanded in open paths and closed loops associated to pure quantum gravity observables. We obtain the vertex amplitudes for gauge-invariant observables, while the expectation values of gauge-variant observables, such as the fermion propagator, are given by the evaluation of particular spin networks.

32 pages, many diagrams, uses psfrag.

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Cited by in corpus (9)

• The Spin Foam Approach to Quantum Gravity
• Group field theory for quantum gravity minimally coupled to a scalar field
• The Complete Barrett-Crane Model and its Causal Structure
• Two-point functions in (loop) quantum cosmology
• The new spin foam models and quantum gravity
• The Quantum Gravity Disk: Discrete Current Algebra
• A topological state sum model for fermions on the circle
• Aspects of quantum gravity
• Topological quantum field theory and quantum gravity