Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A new $F(R)$-gravity model   We propose a new model of modified $F(R)$ gravity theory with the function
$F(R) = (1/\beta) \arcsin(\beta R)$. Constant curvature solutions corresponding
to the flat and de Sitter spacetime are obtained. The Jordan and Einstein
frames are considered; the potential and the mass of the scalar degree of
freedom are found. We show that the flat spacetime is stable and the de Sitter
spacetime is unstable. The slow-roll parameters $\epsilon$, $\eta$, and the
$e$-fold number of the model are evaluated in the Einstein frame. The index of
the scalar spectrum power-law $n_s$ and the tensor-to-scalar ratio $r$ are
calculated. Critical points of autonomous equations for the de Sitter phase and
the matter dominated epoch are found and studied. We obtain the approximate
solution of equations of motion which is the deviation from the de Sitter phase
in the Jordan frame. It is demonstrated that the model passes the matter
stability test.

0
The categories of this paper are: hep-ph
23
The categories of this paper are: solv-int
25
The categories of this paper are: patt-sol
9
The categories of this paper are: nlin
18
The categories of this paper are: econ
6
The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
20
The categories of this paper are: acc-phys
7
The categories of this paper are: hep-th
24
The categories of this paper are: dg-ga
28
The categories of this paper are: alg-geom
16
The categories of this paper are: stat
1
The categories of this paper are: cs
19
The categories of this paper are: eess