Unifying Einstein and Palatini gravities

Journal Article · Tue Feb 15 04:00:00 EST 2011 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.83.044016· OSTI ID:21504984

Amendola, Luca; Enqvist, Kari; Koivisto, Tomi ^[1]

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1. Institut fuer Theoretische Physik, University of Heidelberg, Philosophenweg 16, 69120 Heidelberg (Germany)

We consider a novel class of f(R) gravity theories where the connection is related to the conformally scaled metric g{sub {mu}{nu}=}C(R)g{sub {mu}{nu}} with a scaling that depends on the scalar curvature R only. We call them C theories and show that the Einstein and Palatini gravities can be obtained as special limits. In addition, C theories include completely new physically distinct gravity theories even when f(R)=R. With nonlinear f(R), C theories interpolate and extrapolate the Einstein and Palatini cases and may avoid some of their conceptual and observational problems. We further show that C theories have a scalar-tensor formulation, which in some special cases reduces to simple Brans-Dicke-type gravity. If matter fields couple to the connection, the conservation laws in C theories are modified. The stability of perturbations about flat space is determined by a simple condition on the Lagrangian.

• OSTI ID: 21504984
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 4 Vol. 83; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
CONSERVATION LAWS
DISTURBANCES
FUNCTIONS
GRAVITATION
LAGRANGIAN FUNCTION
METRICS
NONLINEAR PROBLEMS
PERTURBATION THEORY
SCALING
STABILITY