Connected correlators in quantum gravity

Citation
J. Ambjorn et al., Connected correlators in quantum gravity, J HIGH EN P, (2), 1999, pp. NIL_64-NIL_84
Citations number
25
Categorie Soggetti
Physics
Journal title
JOURNAL OF HIGH ENERGY PHYSICS
ISSN journal
10298479 → ACNP
Issue
2
Year of publication
1999
Pages
NIL_64 - NIL_84
Database
ISI
SICI code
1029-8479(19990528):2<NIL_64:CCIQG>2.0.ZU;2-K
Abstract
We discuss the concept of connected, reparameterization invariant matter co rrelators in quantum gravity. We analyze the effect of discretization in tw o solvable cases: branched polymers and two-dimensional simplicial gravity. In both cases the naively defined connected correlators for a fixed volume display an anomalous behavior, which could be interpreted as a long-range order. We suggest that this is in fact only a highly non-trivial finite-siz e effect and propose an improved definition of the connected correlator, wh ich reduces the effect. Using this definition we illustrate the appearance of a long-range spin order in the Ising model on a two-dimensional random l attice in an external magnetic field H, when H --> 0 and beta = beta(C).