Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gluon condensate, modified gravity, and the accelerating Universe   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 \tilde{h}(R,q) in the effective gravitational action.
The aim of this article is to explore the cosmological implications of a
particular nonanalytic term \tilde{h} \propto \eta |R|^{1/2} |q|^{3/4}. With a
quadratic approximation of the gravitating gluon-condensate vacuum energy
density \rho_{V}(q) near the equilibrium value q_{0} and a small coupling
constant \eta of the modified-gravity term \tilde{h}, 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 \bar{w}_{X} which is found to evolve toward the value -1 from above.

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The categories of this paper are: cond-mat
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat
34
The categories of this paper are: chem-ph
14
The categories of this paper are: math-ph
0
The categories of this paper are: hep-ph
23
The categories of this paper are: solv-int
10
The categories of this paper are: q-bio
30
The categories of this paper are: q-alg
17
The categories of this paper are: q-fin
19
The categories of this paper are: eess
2
The categories of this paper are: math
16
The categories of this paper are: stat
28
The categories of this paper are: alg-geom