Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Phantom energy dominated universe as a transient stage in $f(R)$
  cosmology   The $f(R)$ theories of gravity are the most popular, simple and well
succeeded extension of Einstein's General Relativity. They can account for some
observational issues of standard cosmology with no need for evoking the dark
sector of the universe. In the present letter we will investigate LRS Bianchi
type-I space-time in $f(R)$ gravity theory within the phantom energy dominated
era. We show that in this formalism the phantom energy dominated universe is a
transient stage and in the further stage of the universe dynamics, it is
dominated, once again, by dark energy. Such an important feature is obtained
from the model, rather than imposed to it, and may have a relation to loop
quantum cosmology.

16
The categories of this paper are: stat
14
The categories of this paper are: math-ph
25
The categories of this paper are: patt-sol
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
2
The categories of this paper are: math
21
The categories of this paper are: adap-org
28
The categories of this paper are: alg-geom
17
The categories of this paper are: q-fin
11
The categories of this paper are: hep-lat
23
The categories of this paper are: solv-int
32
The categories of this paper are: atom-ph
3
The categories of this paper are: physics
10
The categories of this paper are: q-bio
33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga