Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Geometric Model of Quintessence   On basis of modification of Einstein's gravitational equations by adding the
term $f(R)\propto \beta R^n$, a geometric model of quintessence is proposed.
The evolution equation for the scale factor $a$ of the Universe is analyzed for
the two parameters $n=2$ and $n=4/3$, which were preferred by previous studies
of the early Universe. Another choice of parameters $n$ and $\beta$ is proposed
from the following reasons: the exponent $n$ close to 1.2953 follows from the
request for the evolution of the Universe after recombination to be close to
the evolution of the flat FRW model with cold dark matter and reasonable age of
the Universe defines the value of the coefficient $\beta$. Such a model
corresponding to the evolution of the Universe with the dynamical
$\Lambda$-term describes well enough the observational data.

34
The categories of this paper are: chem-ph
36
The categories of this paper are: cmp-lg
26
The categories of this paper are: bayes-an
7
The categories of this paper are: hep-th
22
The categories of this paper are: chao-dyn
21
The categories of this paper are: adap-org
31
The categories of this paper are: ao-sci
24
The categories of this paper are: dg-ga
37
The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol
28
The categories of this paper are: alg-geom
3
The categories of this paper are: physics
10
The categories of this paper are: q-bio
4
The categories of this paper are: cond-mat
27
The categories of this paper are: comp-gas
13
The categories of this paper are: quant-ph