Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Deep connection between f(R) gravity and the interacting dark sector
  model   We examine the conformal equivalence between the $f(R)$ gravity and the
interacting dark sector model. We review the well-known result that the
conformal transformation physically corresponds to the mass dilation which
marks the strength of interaction between dark sectors. Instead of modeling
f(R) gravity in the Jordan frame, we construct the $f(R)$ gravity in terms of
mass dilation function in the Einstein frame. We find that the condition to
keep $f(R)$ gravity consistent with CMB observations ensures the energy flow
from dark energy to dark matter in the corresponding interacting model, which
meets the requirement to alleviate the coincidence problem in the Einstein
framework.

19
The categories of this paper are: eess
29
The categories of this paper are: funct-an
15
The categories of this paper are: nucl-ex
18
The categories of this paper are: econ
27
The categories of this paper are: comp-gas
20
The categories of this paper are: acc-phys
23
The categories of this paper are: solv-int
30
The categories of this paper are: q-alg
13
The categories of this paper are: quant-ph
36
The categories of this paper are: cmp-lg
31
The categories of this paper are: ao-sci
17
The categories of this paper are: q-fin
4
The categories of this paper are: cond-mat
8
The categories of this paper are: hep-ex
11
The categories of this paper are: hep-lat
16
The categories of this paper are: stat