Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: New Interaction between Dark Energy and Dark Matter Changes Sign during
  Cosmological Evolution   It is found by Cai and Su that the interaction between dark energy and cold
dark matter is likely to change the sign during the cosmological evolution.
Motivated by this, we suggest a new form of interaction between dark energy and
dark matter, which changes from negative to positive as the expansion of our
universe changes from decelerated to accelerated. We find that the interacting
model is consistent with the second law of thermodynamics and the observational
constraints. And, we also discuss the unified adiabatic-squared sound speed of
the model.

8
The categories of this paper are: hep-ex
13
The categories of this paper are: quant-ph
3
The categories of this paper are: physics
25
The categories of this paper are: patt-sol
14
The categories of this paper are: math-ph
11
The categories of this paper are: hep-lat
23
The categories of this paper are: solv-int
35
The categories of this paper are: mtrl-th
32
The categories of this paper are: atom-ph
0
The categories of this paper are: hep-ph
21
The categories of this paper are: adap-org
26
The categories of this paper are: bayes-an
36
The categories of this paper are: cmp-lg
19
The categories of this paper are: eess
20
The categories of this paper are: acc-phys
27
The categories of this paper are: comp-gas