Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A (varying power)-law modified gravity   In the present paper we analyze a toy model for an $f(\phi,R)$ gravity which
has the form of a power-law modified gravity in which the exponent is
space-time dependent. Namely, we investigate the effects of adding to the
Hilbert-Einstein action an $R^{\phi}$-term. We present possible equivalences of
the model with known models of modified gravity theories and examine the
problem of matter stability in this model. Like $f(R)$-gravity toy models, the
present one offers the possibility of unifying the early and the late-time
evolution of the Universe. We show that the behavior of the scalar field
depends globally on the size of the Universe and locally on the surrounding
environment. For the early Universe it lets appear a huge cosmological constant
that might drive inflation. For the late-times it lets appear globally a tiny
cosmological constant.

22
The categories of this paper are: chao-dyn
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
28
The categories of this paper are: alg-geom
10
The categories of this paper are: q-bio
35
The categories of this paper are: mtrl-th
14
The categories of this paper are: math-ph
11
The categories of this paper are: hep-lat
16
The categories of this paper are: stat
26
The categories of this paper are: bayes-an
31
The categories of this paper are: ao-sci
32
The categories of this paper are: atom-ph
37
The categories of this paper are: supr-con
3
The categories of this paper are: physics
7
The categories of this paper are: hep-th
9
The categories of this paper are: nlin