Gluon condensate, modified gravity, and the accelerating Universe

Journal Article · Mon Feb 15 04:00:00 EST 2010 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.81.043006· OSTI ID:21409253

Klinkhamer, F R ^[1]

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1. Institute for Theoretical Physics, University of Karlsruhe, Karlsruhe Institute of Technology, 76128 Karlsruhe (Germany)

It has been suggested recently to study the dynamics of a gravitating gluon condensate q in the context of a spatially flat Friedmann-Robertson-Walker universe. The expansion of the Universe (or, more generally, the presence of a nonvanishing Ricci curvature scalar R) perturbs the gluon condensate and may induce a nonanalytic term h-tilde(R,q) in the effective gravitational action. The aim of this article is to explore the cosmological implications of a particular nonanalytic term h-tilde{proportional_to}{eta}|R|{sup 1/2}|q|{sup 3/4}. With a quadratic approximation of the gravitating gluon-condensate vacuum energy density {rho}{sub V}(q) near the equilibrium value q{sub 0} and a small coupling constant {eta} of the modified-gravity term h-tilde, an 'accelerating universe' is obtained which resembles the present Universe, both qualitatively and quantitatively. The unknown component X of this model universe (here, primarily due to modified-gravity effects) has an effective equation-of-state parameter w{sub X} which is found to evolve toward the value -1 from above.

• OSTI ID: 21409253
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 4 Vol. 81; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
79 ASTRONOMY AND ASTROPHYSICS
APPROXIMATIONS
CALCULATION METHODS
COUPLING CONSTANTS
ENERGY DENSITY
EQUATIONS
EQUATIONS OF STATE
EQUILIBRIUM
EXPANSION
GLUON CONDENSATION
GRAVITATION
UNIVERSE