Some components of the graviton two-point function have been recently computed in the context of loop quantum gravity, using the spinfoam Barrett-Crane vertex. We complete the calculation of the remaining components. We find that, under our assumptions, the Barrett-Crane vertex does not yield the correct long-distance limit. We argue that the problem is general and can be traced to the intertwiner independence of the Barrett-Crane vertex, and therefore to the well-known mismatch between the Barrett-Crane formalism and the standard canonical spin networks. In another paper we illustrate the asymptotic behavior of a vertex amplitude that can correct this difficulty.
|Titolo:||Complete LQG propagator: Difficulties with the barrett-crane vertex|
|Autori:||Alesci E; Rovelli C|
|Rivista:||PHYSICAL REVIEW D, PARTICLES, FIELDS, GRAVITATION, AND COSMOLOGY|
|Data di pubblicazione:||2007|
|Digital Object Identifier (DOI):||10.1103/PhysRevD.76.104012|
|Appare nelle tipologie:||1.1 Journal article|