skip to main content

Title: A caveat on building nonlocal models of cosmology

Nonlocal models of cosmology might derive from graviton loop corrections to the effective field equations from the epoch of primordial inflation. Although the Schwinger-Keldysh formalism would automatically produce causal and conserved effective field equations, the models so far proposed have been purely phenomenological. Two techniques have been employed to generate causal and conserved field equations: either varying an invariant nonlocal effective action and then enforcing causality by the ad hoc replacement of any advanced Green's function with its retarded counterpart, or else introducing causal nonlocality into a general ansatz for the field equations and then enforcing conservation. We point out here that the two techniques access very different classes of models, and that neither one of them may represent what would actually arise from fundamental theory.
Authors:
 [1] ;  [2]
  1. Institute of Theoretical Physics and Computational Physics, Department of Physics, University of Crete, GR-710 03 Heraklion (Greece)
  2. Department of Physics, University of Florida, Gainesville, FL 32611 (United States)
Publication Date:
OSTI Identifier:
22375900
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2014; Journal Issue: 09; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACTION INTEGRAL; CORRECTIONS; COSMOLOGICAL INFLATION; COSMOLOGY; FIELD EQUATIONS; GREEN FUNCTION