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Title: Nonderivative modified gravity: a classification

We analyze the theories of gravity modified by a generic nonderivative potential built from the metric, under the minimal requirement of unbroken spatial rotations. Using the canonical analysis, we classify the potentials V according to the number of degrees of freedom (DoF) that propagate at the nonperturbative level. We then compare the nonperturbative results with the perturbative DoF propagating around Minkowski and FRW backgrounds. A generic V implies 6 propagating DoF at the non-perturbative level, with a ghost on Minkowski background. There exist potentials which propagate 5 DoF, as already studied in previous works. Here, no V with unbroken rotational invariance admitting 4 DoF is found. Theories with 3 DoF turn out to be strongly coupled on Minkowski background. Finally, potentials with only the 2 DoF of a massive graviton exist. Their effect on cosmology is simply equivalent to a cosmological constant. Potentials with 2 or 5 DoF and explicit time dependence appear to be a further viable possibility.
Authors:
 [1] ;  [2] ;  [3]
  1. INFN - Sezione di Ferrara, I-35131 Ferrara (Italy)
  2. Ruđer er Bošković Institute, Bijenička cesta 54, 10000, Zagreb (Croatia)
  3. Dipartimento di Scienze Fisiche e Chimiche, Università di L'Aquila, I-67010 L'Aquila (Italy)
Publication Date:
OSTI Identifier:
22375754
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2014; Journal Issue: 11; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CLASSIFICATION; COMPARATIVE EVALUATIONS; COSMOLOGICAL CONSTANT; COSMOLOGY; DEGREES OF FREEDOM; GRAVITATION; METRICS; MINKOWSKI SPACE; POTENTIALS; ROTATIONAL INVARIANCE; TIME DEPENDENCE