Phys. Rev. D 78, 104023 (2008) [18 pages]Semiclassical limit of 4-dimensional spin foam modelsReceived 16 September 2008; published 19 November 2008 We study the semiclassical properties of the Riemannian spin foam models with Immirzi parameter that are constructed via coherent states. We show that, in the semiclassical limit, the quantum spin foam amplitudes of an arbitrary triangulation are exponentially suppressed if the face spins do not correspond to a discrete geometry. When they do arise from a geometry, the amplitudes reduce to the exponential of i times the Regge action. Remarkably, the dependence on the Immirzi parameter disappears in this limit. © 2008 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevD.78.104023
DOI:
10.1103/PhysRevD.78.104023
PACS:
04.60.Pp, 04.60.Gw
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