Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Exact solution and exotic fluid in cosmology   We investigate cosmological consequences of nonlinear sigma model coupled
with a cosmological fluid which satisfies the continuity equation. The target
space action is of de Sitter type and is composed of four scalar fields. The
potential which is a function of only one of the scalar fields is also
introduced. We perform a general analysis of the ensuing cosmological equations
and give various critical points and their properties. Then, we show that the
model exhibits exact cosmological solution which yields a transition from
matter domination into dark energy and compare it with the $\Lambda$CDM
behavior. Especially, we calculate the age of the Universe and show that it is
consistent with the observational value if the equation of the state $\omega_f$
for the cosmological fluid is within the range of $0.13 < \omega_f < 0.22.$
Some implication of this result is also discussed.

1
The categories of this paper are: cs
34
The categories of this paper are: chem-ph
35
The categories of this paper are: mtrl-th
24
The categories of this paper are: dg-ga
30
The categories of this paper are: q-alg
23
The categories of this paper are: solv-int
9
The categories of this paper are: nlin
37
The categories of this paper are: supr-con
19
The categories of this paper are: eess
16
The categories of this paper are: stat
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
36
The categories of this paper are: cmp-lg
17
The categories of this paper are: q-fin
25
The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph