Schedule Oct 07, 2021
Comments on wormholes and factorization
Phil Saad, IAS
Cite as: doi:10.26081/K6B05V

In AdS/CFT partition functions of decoupled copies of the CFT factorize. In bulk computations of such quantities contributions from spacetime wormholes which link separate asymptotic boundaries threaten to spoil this property, leading to a "factorization puzzle." Certain simple models like JT gravity and the SYK model have wormholes, but bulk computations in them correspond to averages over an ensemble of boundary systems. These averages need not factorize. We can formulate a toy version of the factorization puzzle in such models by focusing on a specific member of the ensemble, for which partition functions will factorize. In the bulk, these fixed members of the ensemble correspond to "alpha states" of many closed universes. In this talk we discuss bulk computations of partition functions in (sometimes approximate) alpha states in three simple models: the topological model introduced by Marolf and Maxfield (the "MM model"), JT gravity, and the SYK model, and give an effective description of the factorization mechanism.

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