Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Cosmological Solutions of a Nonlocal Model with a Perfect Fluid   A nonlocal gravity model which does not assume the existence of a new
dimensional parameter in the action and includes a function $f(\Box^{-1} R)$,
with $\Box$ the d'Alembertian operator, is studied. By specifying an
exponential form for the function f and including a matter sector with a
constant equation of state parameter, all available power-law solutions in the
Jordan frame are obtained. New power-law solutions in the Einstein frame are
also probed. Furthermore, the relationship between power-law solutions in both
frames, established through conformal transformation, is substantially
clarified. The correspondence between power-law solutions in these two frames
is proven to be a very useful tool in order to obtain new solutions in the
Einstein frame.

9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
30
The categories of this paper are: q-alg
3
The categories of this paper are: physics
25
The categories of this paper are: patt-sol
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs
16
The categories of this paper are: stat
15
The categories of this paper are: nucl-ex
32
The categories of this paper are: atom-ph
2
The categories of this paper are: math
29
The categories of this paper are: funct-an
36
The categories of this paper are: cmp-lg
26
The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn