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The basis of the Ponzano-Regge-Turaev-Viro-Ooguri model is the loop representation basis

Carlo Rovelli
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Abstract

We show that the Hilbert space basis that defines the Ponzano-Regge- Turaev-Viro-Ooguri combinatorial definition of 3-d Quantum Gravity is the same as the one that defines the Loop Representation. We show how to compute lengths in Witten's 3-d gravity and how to reconstruct the 2-d geometry from a state of Witten's theory. We show that the non-degenerate geometries are contained in the Witten's Hilbert space. We sketch an extension of the combinatorial construction to the physical 4-d case, by defining a modification of Regge calculus in which areas, rather than lengths, are taken as independent variables. We provide an expression for the scalar product in the Loop representation in 4-d. We discuss the general form of a nonperturbative quantum theory of gravity, and argue that it should be given by a generalization of Atiyah's topological quantum field theories axioms.

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Carlo Rovelli. 1993-05-01. The basis of the Ponzano-Regge-Turaev-Viro-Ooguri model is the loop representation basis. https://doi.org/10.1103/physrevd.48.2702

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